Ambient air - Standard method for the measurement of the concentration of ozone by ultraviolet photometry

This European Standard specifies a continuous measurement method for the determination of the concentrations of ozone present in ambient air based on the ultraviolet photometric measuring principle. This standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate ultraviolet photometric analyser by means of type approval tests. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site so as to meet the data quality requirements as specified in Annex I of Directive 2008/50/EC and requirements during sampling, calibration and quality assurance for use. The method is applicable to the determination of the concentration of ozone present in ambient air up to 500 μg/m3. This concentration range represents the certification range for ozone for the type approval test. The method covers the determination of ambient air concentrations of ozone in zones classified as rural areas, urban and urban-background areas. The results are expressed in μg/m3 (at 20 °C and 101,3 kPa). This standard contains information for different groups of users. Clauses 5 to 7 and Annexes B and C contain general information about the principles of ozone measurement by ultraviolet photometric analyser and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of ozone analysers. These sections contain information about: - type-approval test conditions, test procedures and test requirements; - analyser performance requirements; - evaluation of the type-approval test results; - evaluation of the uncertainty of the measurement results of the ozone analyser based on the type-approval test results. Clauses 9 to 11 and Annexes F and G are directed towards monitoring networks performing the practical measurements of ozone in ambient air. These sections contain information about: - initial installation of the analyser in the monitoring network and acceptance testing; - ongoing quality assurance/quality control; - calculation and reporting of measurement results; - evaluation of the uncertainty of measurement results under practical monitoring conditions.

Luftqualität - Messverfahren zur Bestimmung der Konzentration von Ozon mit Ultraviolett-Photometrie

Diese Europäische Norm legt ein kontinuierliches ultraviolettphotometrisches Messverfahren zur Bestimmung der Konzentration von Ozon in Luft fest. Es nennt die Leistungs¬kenngrößen und legt die Mindest¬anforde-rungen für die Eignungsprüfung von photometrischen Messgeräten fest. Es beinhaltet auch die Bewertung der Eignung eines Messgeräts für den Einsatz an einem bestimmten ortsfesten Messstandort bezüglich der Anforderungen an die Datenqualität nach Anhang I der Richtlinie 2008/50/EG [1] und bezüglich der Anforderungen für Probennahme, Kalibrierung und Qualitätssicherung.
Das Verfahren ist anwendbar zur Bestimmung der Massenkonzentration von Ozon in Luft im Bereich bis 500 µg/m3. Dieser Konzentrationsbereich entspricht dem Zertifizierungsbereich für die Eignungsprüfung.
ANMERKUNG 1   Für ländliche Standorte zur Überwachung von Ökosystemen können auch andere Bereiche gewählt werden.
ANMERKUNG 2   Wird diese Norm für andere Zwecke als für Messungen nach Richtlinie 2008/50/EG eingesetzt, dann brauchen die Anforderungen hinsichtlich Anwendungsbereich und Unsicherheit nicht zur Geltung kommen.
Das Verfahren umfasst die Bestimmung der Konzentration von Ozon an Standorten, die als ländlich, städtisch und städtischer Hintergrund klassifiziert sind.
Die Ergebnisse werden in µg/m3 (bei 20 °C und 101,3 kPa) angegeben.
ANMERKUNG 3   500 µg/m3 Ozon entsprechen 250 nmol/mol Ozon bei 20 °C und 101,3 kPa.
Dieses Dokument enthält Informationen für verschiedene Nutzergruppen.
Die Abschnitte 5 bis 7 und die Anhänge B und C enthalten allgemeine Informationen über die Grundlagen der Ozon-Messung mit einem Ultraviolett-Photometer sowie über die Probennahmeeinrichtung.
Abschnitt 8 und Anhang E richten sich speziell an Prüfinstitute und -laboratorien, die Eignungsprüfungen von Ozon-Messgeräten durchführen. Diese Abschnitte enthalten Informationen über
-   Prüfbedingungen, -verfahren und -anforderungen bei der Eignungsprüfung;
-   Anforderungen an die Leistungsfähigkeit des Messgeräts;
-   die Bewertung der Ergebnisse der Eignungsprüfung;
-   die Bewertung der Unsicherheit der Messergebnisse des Ozon-Messgeräts anhand der Eignungs¬prüfungs-ergebnisse.
Die Abschnitte 9 bis 11 und die Anhänge F und G richten sich an die Betreiber von Messnetzen, mit denen Ozon-Messungen in Luft durchgeführt werden. Diese Abschnitte enthalten Informationen über
-   die Erstinstallation des Messgeräts im Messnetz und Eignungsbewertung;
-   die laufende Qualitätssicherung und -kontrolle;
-   die Berechnung und Übermittlung der Messergebnisse;
-   die Bewertung der Unsicherheit der Messergebnisse unter Messbedingungen.

Air ambiant - Méthode normalisée de mesurage de la concentration en ozone par photométrie U.V.

La présente Norme européenne spécifie une méthode de mesurage en continu pour la détermination de la concentration en ozone dans l’air ambiant, selon le principe de mesure par photométrie U.V. La présente norme décrit les caractéristiques de performance et fixe les critères minimaux requis pour sélectionner un analyseur par photométrie U.V. à l’aide d’essais d’approbation de type. Elle présente également l’évaluation de l’aptitude à l’emploi d’un analyseur sur un site fixe spécifique de manière à répondre aux exigences de qualité des données telles que spécifiées dans l’Annexe I de la Directive 2008/50/CE [1] ainsi qu’aux exigences à observer au cours du prélèvement, de l’étalonnage et de l’assurance qualité.
La méthode s’applique à la détermination de la concentration en ozone présent dans l’air ambiant jusqu’à 500 µg/m3. Cette plage de concentration représente l’étendue de mesure certifiée de l’ozone pour l’essai d’approbation de type.
NOTE 1   D’autres plages peuvent être utilisées pour les systèmes de mesure appliqués aux zones rurales contrôlant des écosystèmes.
NOTE 2   Lorsque la norme est utilisée à d’autres fins que la Directive 2008/50/CE, les exigences relatives aux plages et à l’incertitude peuvent ne pas être appliquées.
La méthode s’applique à la détermination des concentrations en ozone présent dans l’air ambiant dans les zones classées comme zones rurales, urbaines et périurbaines.
Les résultats sont exprimés en µg/m3 (à 20 °C et 101,3 kPa).
NOTE 3   500 µg/m3 d’O3 correspondent à 250 nmol/mol d’O3 à 20 °C et 101,3 kPa.
La présente norme contient des informations pour différents groupes d’utilisateurs.
Les Articles 5 à 7 et les Annexes B et C contiennent des informations générales relatives aux principes de mesure de l’ozone à l’aide d’un analyseur par photométrie U.V. et d’un équipement de prélèvement.
L’Article 8 et l’Annexe E concernent tout particulièrement les organismes et les laboratoires d’essai qui effectuent des essais d’approbation de type des analyseurs d’ozone. Ces sections contiennent des informations concernant :
-   les conditions de l’essai d’approbation de type, les modes opératoires d’essai et les exigences d’essai ;
-   les exigences de performance de l’analyseur ;
-   l’évaluation des résultats de l’essai d’approbation de type ;
-   l’évaluation de l’incertitude des résultats de mesurage de l’analyseur d’ozone d’après les résultats de l’essai d’approbation de type.
Les Articles 9 à 11 et les Annexes F et G concernent les réseaux de surveillance effectuant les mesurages pratiques de l’ozone dans l’air ambiant. Ces sections contiennent des informations concernant :
-   l’installation initiale de l’analyseur dans le réseau de surveillance et l’essai de réception ;
-   l’assurance qualité/le contrôle qualité en continu ;
-   le calcul et le compte-rendu des résultats de mesurage ;
-   l’évaluation de l’incertitude des résultats de mesurage sous des conditions de surveillance pratiques.

Zunanji zrak - Standardna metoda za določevanje koncentracije ozona z ultravijolično fotometrijo

Ta evropski standard določa metodo stalnega merjenja za določitev koncentracij ozona v zunanjem zraku na podlagi ultravijoličnega fotometričnega merilnega principa. Ta standard opisuje lastnosti delovanja in vzpostavlja ustrezna minimalna merila, potrebna za izbor ustreznega ultravijoličnega fotometričnega analizatorja s homologacijskimi preizkusi. Vključuje tudi oceno ustreznosti analizatorja za uporabo na specifičnem fiksnem mestu, da se izpolnijo zahteve o kakovosti podatkov, kot je opredeljeno v Prilogi I Direktive 2008/50/ES, ter zahteve med vzorčenjem, kalibriranjem in zagotavljanjem kakovosti za uporabo. Ta metoda velja za določitev koncentracije ozona v zunanjem zraku do vrednosti 500 μg/m3. Ta razpon koncentracij predstavlja razpon certificiranja za ozon za homologacijski preizkus. Ta metoda pokriva določitev koncentracij ozona v zunanjem zraku na področjih, ki so uvrščena med podeželska območja, mestna območja in območja v urbanem okolju. Rezultati so izraženi v μg/m3 (pri 20 °C in 101,3 kPa). Ta standard vsebuje informacije za različne skupine uporabnikov. Določbe od 5 do 7 ter dodatka B in C vsebujejo splošne informacije o načelih merjenja ozona z ultravijoličnimi fotometričnimi analizatorji in opremo za vzorčenje. Osrednji predmet obravnave določbe 8 in dodatka E so laboratoriji, ki izvajajo homologacijsko preizkušanje ozonskih analizatorjev. Ti razdelki vsebujejo informacije o naslednjem: – pogoji homologacijskih preizkusov, preizkusni postopki in zahteve; – zahteve glede učinkovitosti analizatorja; ocena rezultatov homologacijskih preizkusov; ocena negotovosti rezultatov merjenja ozonskega analizatorja na podlagi rezultatov homologacijskih preizkusov. Osrednji predmet obravnave določb od 9 do 11 ter dodatkov F in G so omrežja za spremljanje stanja, ki izvajajo praktične meritve ozona v zunanjem zraku. Ti razdelki vsebujejo informacije o naslednjem: – začetna namestitev analizatorja v omrežju za spremljanje stanja in preizkušanje ustreznosti; – tekoče zagotavljanje kakovosti/nadzor kakovosti; izračun in poročanje rezultatov merjenja; ocena negotovosti rezultatov merjenja pod pogoji praktičnega spremljanja.

General Information

Status
Published
Public Enquiry End Date
19-May-2010
Publication Date
13-Nov-2012
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
16-Oct-2012
Due Date
21-Dec-2012
Completion Date
14-Nov-2012

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Luftqualität - Messverfahren zur Bestimmung der Konzentration von Ozon mit Ultraviolett-PhotometrieAir ambiant - Méthode normalisée de mesurage de la concentration en ozone par photométrie U.V.Ambient air - Standard method for the measurement of the concentration of ozone by ultraviolet photometry13.040.20Kakovost okoljskega zrakaAmbient atmospheresICS:Ta slovenski standard je istoveten z:EN 14625:2012SIST EN 14625:2012en,fr,de01-december-2012SIST EN 14625:2012SLOVENSKI

STANDARDSIST EN 14625:20051DGRPHãþD
SIST EN 14625:2012
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14625
August 2012 ICS 13.040.20 Supersedes EN 14625:2005English Version

Ambient air - Standard method for the measurement of the concentration of ozone by ultraviolet photometry

Air ambiant - Méthode normalisée de mesurage de la concentration en ozone par photométrie U.V.

Luftqualität - Messverfahren zur Bestimmung der Konzentration von Ozon mit Ultraviolett-Photometrie This European Standard was approved by CEN on 10 May 2012.

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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 14625:2012: ESIST EN 14625:2012

EN 14625:2012 (E) 2

Contents Contents ...................................................................................................................................................................... 2Foreword ...................................................................................................................................................................... 41Scope .............................................................................................................................................................. 52Normative references .................................................................................................................................... 63Terms and definitions ................................................................................................................................... 64Abbreviated terms ....................................................................................................................................... 115Principle ........................................................................................................................................................ 115.1General .......................................................................................................................................................... 115.2Measuring principle ..................................................................................................................................... 115.3Type approval test ....................................................................................................................................... 125.4Field operation and quality control ............................................................................................................ 126Sampling ....................................................................................................................................................... 126.1General .......................................................................................................................................................... 126.2Sampling location ........................................................................................................................................ 136.3Sampling system ......................................................................................................................................... 136.4Control and regulation of sample flow rate .............................................................................................. 146.5Sampling pump for the manifold ................................................................................................................ 147Analyser equipment .................................................................................................................................... 147.1General .......................................................................................................................................................... 147.2Ultraviolet absorption cell ........................................................................................................................... 157.3Ultraviolet source lamp ............................................................................................................................... 157.4UV detector ................................................................................................................................................... 157.5Ozone-specific scrubber ............................................................................................................................. 157.6Switching valve ............................................................................................................................................ 157.7Temperature indicator ................................................................................................................................. 157.8Pressure indicator ....................................................................................................................................... 157.9Flow rate indicator ....................................................................................................................................... 167.10Sampling pump for the analyser ................................................................................................................ 167.11Internal ozone span source ........................................................................................................................ 167.12Particle filter ................................................................................................................................................. 168Type approval of ultraviolet photometric ozone analysers ..................................................................... 168.1General .......................................................................................................................................................... 168.2Relevant performance characteristics and performance criteria ........................................................... 178.3Design change ............................................................................................................................................. 18SIST EN 14625:2012

EN 14625:2012 (E) 3 8.4Procedures for determination of the performance characteristics during the laboratory test ........... 198.5Determination of the performance characteristics during the field test ................................................ 308.6Type approval and uncertainty calculation............................................................................................... 339Field operation and ongoing quality control ............................................................................................ 349.1General.......................................................................................................................................................... 349.2Suitability evaluation ................................................................................................................................... 349.3Initial installation ......................................................................................................................................... 369.4Ongoing quality assurance/quality control............................................................................................... 379.5Calibration of the analyser.......................................................................................................................... 389.6Checks .......................................................................................................................................................... 409.7Maintenance ................................................................................................................................................. 449.8Data handling and data reports .................................................................................................................. 449.9Measurement uncertainty ........................................................................................................................... 4510Expression of results .................................................................................................................................. 4511Test reports and documentation ................................................................................................................ 4511.1Type approval test ....................................................................................................................................... 4511.2Field operation ............................................................................................................................................. 47Annex A (normative)

Test of lack of fit ................................................................................................................... 48Annex B (informative)

Sampling equipment........................................................................................................... 50Annex C (informative)

Ultraviolet photometric analyser ....................................................................................... 52Annex D (informative)

Manifold testing equipment ............................................................................................... 54Annex E (normative)

Type approval ........................................................................................................................ 56Annex F (informative)

Calculation of uncertainty in field operation at the hourly alert threshold value ......... 75Annex G (informative)

Calculation of uncertainty in field operation at the 8-hour target value ....................... 83Annex H (informative)

Significant technical changes ........................................................................................... 93Bibliography .............................................................................................................................................................. 94 SIST EN 14625:2012

EN 14625:2012 (E) 4 Foreword This document (EN 14625:2012) has been prepared by Technical Committee CEN/TC 264 “Air quality”, the secretariat of which is held by DIN. 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 February 2013, and conflicting national standards shall be withdrawn at the latest by February 2013. 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. This document supersedes EN 14625:2005. The technical changes made since EN 14625:2005 are listed in Annex H of this European Standard.

According to the CEN/CENELEC Internal Regulations, the national standards organisations 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 14625:2012

EN 14625:2012 (E) 5 1 Scope This European Standard specifies a continuous measurement method for the determination of the concentrations of ozone present in ambient air based on the ultraviolet photometric measuring principle. This standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate ultraviolet photometric analyser by means of type approval tests. It also includes the evaluation of the suitability of an analyser for use in a specific fixed site so as to meet the data quality requirements as specified in Annex I of Directive 2008/50/EC [1] and requirements during sampling, calibration and quality assurance for use. The method is applicable to the determination of the concentration of ozone present in ambient air up to 500 µg/m3. This concentration range represents the certification range for ozone for the type approval test. NOTE 1 Other ranges may be used for measurement systems applied at rural locations monitoring ecosystems. NOTE 2 When the standard is used for other purposes than Directive 2008/50/EC, the ranges and uncertainty requirements may not apply. The method covers the determination of ambient air concentrations of ozone in zones classified as rural areas, urban and urban-background areas.

The results are expressed in µg/m3 (at 20 °C and 101,3 kPa). NOTE 3 500 µg/m3 of O3 corresponds to 250 nmol/mol of O3 at 20 °C and 101,3 kPa. This standard contains information for different groups of users. Clauses 5 to 7 and Annexes B and C contain general information about the principles of ozone measurement by ultraviolet photometric analyser and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of ozone analysers. These sections contain information about:  type-approval test conditions, test procedures and test requirements;  analyser performance requirements;  evaluation of the type-approval test results;  evaluation of the uncertainty of the measurement results of the ozone analyser based on the type-approval test results. Clauses 9 to 11 and Annexes F and G are directed towards monitoring networks performing the practical measurements of ozone in ambient air. These sections contain information about:  initial installation of the analyser in the monitoring network and acceptance testing;  ongoing quality assurance/quality control;  calculation and reporting of measurement results;  evaluation of the uncertainty of measurement results under practical monitoring conditions.

SIST EN 14625:2012

EN 14625:2012 (E) 6 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 15267-1, Air quality — Certification of automated measuring systems — Part 1: General principles EN 15267-2, Air quality — Certification of automated measuring systems — Part 2: Initial assessment of the AMS manufacturer’s quality management system and post certification surveillance for the manufacturing process EN ISO 6145-6, Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods — Part 6: Critical orifices (ISO 6145-6) EN ISO 6145-7, Gas analysis — Preparation of calibration gas mixtures using dynamic volumetric methods — Part 7: Thermal mass-flow controllers (ISO 6145-7) EN ISO 14956, Air quality — Evaluation of the suitability of a measurement procedure by comparison with a required measurement uncertainty (ISO 14956) EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

(ISO/IEC 17025) ENV 13005:1999, Guide to the expression of uncertainty in measurement ISO 13964:1998, Air quality — Determination of ozone in ambient air — Ultraviolet photometric method 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 adjustment set of operations carried out on a measuring system so that it provides prescribed indications corresponding to given values of a quantity to be measured

Note 1 to entry

Types of adjustment of a measuring system include zero adjustment of a measuring system, offset adjustment, and span adjustment (sometimes called gain adjustment). Note 2 to entry

Adjustment of a measuring system should not be confused with calibration, which is a prerequisite for adjustment. [SOURCE: JCGM 200:2012 (VIM) [2]] Note 3 to entry

In the context of this standard, adjustment is performed on measurement data rather than on the analyser. 3.2 alert threshold level beyond which there is a risk to human health from brief exposure for the population as a whole and at which immediate steps are to be taken by the Member States [SOURCE: 2008/50/EC [1]] 3.3 ambient air outdoor air in the troposphere, excluding workplaces as defined by Directive 89/654/EEC, where provisions concerning health and safety at work apply and to which members of the public do not have regular access [SOURCE: 2008/50/EC [1]] SIST EN 14625:2012

EN 14625:2012 (E) 7 3.4 analyser measuring system that provides an output signal which is a function of the concentration, partial pressure, flow or temperature of one or more components of a gas mixture 3.5 availability of the analyser fraction of the total time period for which usually valid measuring data of the ambient air concentration is available from an analyser

3.6 calibration operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication

Note 1 to entry: A calibration may be expressed by a statement, calibration function, calibration diagram, calibration curve, or calibration table. In some cases, it may consist of an additive or multiplicative correction of the indication with associated measurement uncertainty. Note 2 to entry:

Calibration should not be confused with adjustment of a measuring system, often mistakenly called “self-calibration”, nor with verification of a calibration. Note 3 to entry: Often, the first step alone in the above definition is perceived as being calibration. [SOURCE: JCGM 200:2008 (VIM) [2]] Note 4 to entry: In the context of this standard, calibration is a comparison of the analyser response to a known gas concentration with a known uncertainty when the information obtained from the comparison is used for the successive adjustment (if needed) of the analyser. 3.7 certification range concentration range for which the analyser is type-approved 3.8 check verification that the analyser is still operating within specified performance limits

3.9 combined standard uncertainty standard uncertainty of the result of a measurement when that result is obtained from the values of a number of other quantities, equal to the positive square root of a sum of terms, the terms being the variances or co-variances of these other quantities weighted according to how the measurement result varies with changes in these quantities [SOURCE: ENV 13005:1999] 3.10 coverage factor numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an expanded uncertainty [SOURCE: ENV 13005:1999] 3.11 designated body body which has been designated for a specific task (type approval tests and/or QA/QC activities in the field) by the competent authority in the Member States

SIST EN 14625:2012

EN 14625:2012 (E) 8 3.12 detection limit smallest concentration of a measurand that can be reliably detected by a specific measurement process Note 1 to entry: The detection limit is calculated as 3,3 x (sz/B) where sz is the standard deviation of analyser response at zero measurand concentration (see 8.4.5) and B is the slope of the calibration function [3]. 3.13 expanded uncertainty quantity defining an interval about the result of a measurement that may be expected to encompass a large fraction of the distribution of values that could reasonably be attributed to the measurand Note 1 to entry:

The fraction may be viewed as the coverage probability or level of confidence of the interval. Note 2 to entry:

To associate a specific level of confidence with the interval defined by the expanded uncertainty requires explicit or implicit assumptions regarding the probability distribution characterised by the measurement result and its combined standard uncertainty. The level of confidence that may be attributed to this interval can be known only to the extent to which such assumptions may be justified. [SOURCE: ENV 13005:1999] Note 3 to entry: For the purpose of this European Standard, the expanded uncertainty is the combined standard uncertainty multiplied by a coverage factor k=2 resulting in an interval with a level of confidence of 95 %. 3.14 fall time difference between the response time (fall) and the lag time (fall) 3.15 independent measurement individual measurement that is not influenced by a previous individual measurement by separating two individual measurements by at least four response times Note 1 to entry: The largest value of response time (rise) and response time (fall) are intended. 3.16 individual measurement measurement averaged over a time period equal to the response time of the analyser Note 1 to entry: The largest value of response time (rise) and response time (fall) are intended. Note 2 to entry: This definition differs from the meaning of the concept “individual measurement” in Directive 2008/50/EC [1]. 3.17 influence quantity quantity that is not the measurand but that affects the result of the measurement

[SOURCE: ENV 13005:1999] 3.18 interferent component of the air sample, excluding the measured constituent, that affects the output signal 3.19 lack of fit maximum deviation from the linear regression line of the average of a series of measurement results at the same concentration

SIST EN 14625:2012

EN 14625:2012 (E) 9 3.20 lag time time interval from the moment at which a step change of sample concentration occurs at the inlet of the analyser to the moment at which the output reading reaches a level corresponding to a predefined change of the stable output reading 3.21 long term drift difference between zero or span readings over a determined period of time (e.g. period of unattended operation) 3.22 monitoring station enclosure located in the field in which an analyser has been installed to monitor concentrations

3.23 parallel measurements measurements from different analysers, sampling from one and the same sampling manifold, starting at the same time and ending at the same time 3.24 performance characteristic one of the parameters assigned to equipment in order to define its performance 3.25 performance criterion limiting quantitative numerical value assigned to a performance characteristic, to which conformance is tested 3.26 period of unattended operation time period over which the drift is within the performance criterion for long term drift 3.27 repeatability (of results of measurement) closeness of the agreement between the results of successive individual measurements of ozone carried out under the same conditions of measurement Note 1 to entry: These conditions are called laboratory repeatability conditions and include: a) the same measurement procedure; b)

the same observer; c)

the same analyser, used under the same conditions; d) at the same location; e) repetition over a short period of time. 3.28 reproducibility under field conditions closeness of the agreement between the results of simultaneous measurements with two analysers in ambient air carried out under the same conditions of measurement Note 1 to entry: These conditions are called field reproducibility conditions and include: a) the same measurement procedure; b)

two identical analysers, used under the same conditions; c) at the same monitoring station; d) the period of unattended operation. 3.29 residence time inside the analyser time period for the sampled air to be transported from the inlet of the analyser to the UV absorption cell SIST EN 14625:2012

EN 14625:2012 (E) 10 3.30 residence time in the sampling system time period for the sampled air to be transferred to the inlet of the analyser 3.31 response time time interval from the instant at which a step change of sample concentration occurs at the inlet of the analyser to the instant at which the output reading reaches a level corresponding to a predefined change of the output reading 3.32 sampled air part of ambient air that is transferred through the sampling inlet and sampling system for subsequent measurement 3.33 sample gas temperature temperature of the sampled gas at the sample inlet

Note 1 to entry: The term ‘gas’ may refer to a test gas used in type-approval testing or to ambient air transferred to the analyser.

3.34 sampling system the assembly of components needed to transfer ambient air to the analyser 3.35 short-term drift difference between zero or span readings at the beginning and end of a 12 h period 3.36 standard uncertainty uncertainty of the result of a measurement expressed as a standard deviation

[SOURCE: ENV 13005:1999] 3.37 surrounding temperature temperature of the air directly surrounding the analyser 3.38 target value level fixed with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained where possible over a given period [SOURCE: 2008/50/EC [1]] 3.39 total residence time sum of the residence time in the sampling system and the residence time inside the analyser 3.40 type approval decision taken by a designated body that the pattern of an analyser conforms to specified requirements 3.41 type approval test examination of two or more analysers of the same pattern which are submitted by a manufacturer to a designated body including the tests necessary for approval of the pattern SIST EN 14625:2012

EN 14625:2012 (E) 11 3.42 uncertainty (of measurement) parameter associated with the result of a measurement that characterises the dispersion of the values that could be attributed to the measurand [SOURCE: ENV 13005:1999] 4 Abbreviated terms

FEP
perfluoro-ethylene-propylene; MFC mass flow controller; PFA

perfluoroalkoxy (polymer resin); PTFE polytetrafluoroethylene. 5 Principle 5.1 General This standard describes the method for measurement of the concentrations of ozone in ambient air by means of ultraviolet photometry. The requirements, the specific components of the ultraviolet photometric analyser and its sampling system are described. A number of performance characteristics with associated minimum performance criteria are given for the analyser. The actual values of these performance characteristics for a specific type of analyser shall be determined in a so-called type approval test for which procedures have been described. The type approval test comprises a laboratory test and a field test. The selection of a type-approved analyser for a specific measuring task in the field is based on the calculation of the expanded uncertainty of the measurement method. In this expanded uncertainty calculation, the actual values of various performance characteristics of a type-approved analyser and the site-specific conditions at the monitoring station are taken into account (see 9.6). The expanded uncertainty of the method shall not exceed 15 % for fixed measurements or 30% for indicative measurements, as specified in Directive 2008/50/EC [1]. Requirements and recommendations for quality assurance and quality control are given for the measurements in the field (see 9.4). 5.2 Measuring principle Sampled air is drawn continuously through an optical absorption cell where it is irradiated by monochromatic radiation, centred on 253,7 nm, from a stabilised low-pressure mercury (Hg) discharge lamp. The UV radiation, which passes through the absorption cell, is measured by a sensitive photodiode or photomultiplier detector and converted to a measurable electrical signal. Absorption of this radiation by the sampled air within the absorption cell is a measure of the ozone concentration in the ambient air. Two different systems for the measurement of the ultraviolet absorption by ozone are usually employed. In one system, the ultraviolet absorption by ozone is determined by means of the difference in ultraviolet absorption between a sample cell and a reference cell (dual-cell type). In the other system, only a single

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