EN 14662-3:2015
(Main)Ambient air - Standard method for the measurement of benzene concentrations - Part 3: Automated pumped sampling with in situ gas chromatography
Ambient air - Standard method for the measurement of benzene concentrations - Part 3: Automated pumped sampling with in situ gas chromatography
This European Standard specifies a semi-continuous measurement method for the determination of the concentration of benzene present in ambient air based on automated sampling and analysis by gas chromatography. This standard describes the performance characteristics and sets the relevant minimum criteria required to select an appropriate automated gas chromatograph (GC) 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 mass con¬centration of benzene present in ambient air in the range up to 50 µg/m3 benzene. This concentration range represents the certification range for the type approval test.
Other ranges may be used depending on the levels present in ambient air.
NOTE 1 When the standard is used for other purposes than for measurements required by Directive 2008/50/EC, the ranges and uncertainty requirements may not apply.
The method covers the determination of ambient air concentrations of benzene in zones classified as rural areas, urban-background areas and traffic-orientated locations and locations influenced by industrial sources.
The results are expressed in µg/m3 (at 20 °C and 101,3 kPa).
NOTE 2 50 µg/m3 of benzene corresponds to 15,4 nmol/mol of benzene.
This European Standard contains information for different groups of users.
Clauses 5 to 7 and Annexes C and D contain general information about the principles of benzene measurement by automated gas chromatography and sampling equipment.
Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of benzene 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 benzene analyser based on the type-approval test results.
Clauses 9 to 11 and Annex F are directed towards monitoring networks performing the practical measurements of benzene 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.
Außenluft - Messverfahren zur Bestimmung von Benzolkonzentrationen - Teil 3: Automatische Probenahme mit einer Pumpe und gaschromatographische In-situ-Bestimmung
Diese Europäische Norm legt ein quasikontinuierliches Messverfahren zur Bestimmung der Konzentration von Benzol in Außenluft mit automatisierter Probenahme und gaschromatographischer Analyse fest. Diese Norm beschreibt die Leistungskenngrößen und legt die betreffenden Mindestkriterien für die Eignungsprüfung eines automatischen Gaschromatographen (GC) fest. Sie beinhaltet auch die Bewertung der Eignung eines Messgeräts für die Anwendung an einem ortsfesten Messstandort bezüglich der Anforderungen an die Datenqualität nach Anhang I der Richtlinie 2008/50/EG [1] und bezüglich der Anforderungen an Probenahme, Kalibrierung und Qualitätssicherung.
Das Verfahren ist anwendbar zur Bestimmung der Massenkonzentration von Benzol in Außenluft bis 50 µg/m3. Dieser Konzentrationsbereich entspricht dem Zertifizierungsbereich der Eignungsprüfung.
Abhängig von den in Außenluft vorliegenden Konzentrationen dürfen auch andere Bereiche gewählt werden.
ANMERKUNG 1 Wird die Norm für andere Zwecke als die von der Richtlinie 2008/50/EG geforderten Messungen angewendet, brauchen die Bereiche und Anforderungen an die Unsicherheit nicht zur Anwendung zu kommen.
Das Verfahren umfasst die Bestimmung der Konzentrationen von Benzol in Außenluft an Standorten, die als ländlich, städtischer Hintergrund, verkehrsbezogen und von industriellen Quellen beeinflusst eingestuft werden.
Die Ergebnisse werden in µg/m3 (bei 20 °C und 101,3 kPa) angegeben.
ANMERKUNG 2 50 µg/m3 Benzol entsprechen 15,4 nmol/mol Benzol.
Diese Norm enthält Informationen für verschiedene Anwendergruppen.
Die Abschnitte 5 bis 7 und die Anhänge C und D enthalten allgemeine Angaben zur Messung von Benzol mit automatischer Gaschromatographie und Probenahmeeinrichtung.
Abschnitt 8 und Anhang E richten sich an Prüfstellen und laboratorien, die Eignungsprüfungen von Benzol-Messgeräten durchführen. Diese Abschnitte enthalten Angaben über:
- Prüfbedingungen, -verfahren und -anforderungen der Eignungsprüfung;
- Anforderungen an die Leistungsfähigkeit des Messgeräts;
- die Bewertung der Ergebnisse der Eignungsprüfung;
- die Bewertung der Unsicherheit der Messergebnisse des Benzol-Messgeräts auf der Grundlage der Ergebnisse der Eignungsprüfung.
Die Abschnitte 9 bis 11 und Anhang F richten sich an die Betreiber von Messnetzen, in denen Benzol-Messungen in Außenluft durchgeführt werden. Diese Abschnitte enthalten Angaben über:
- die Erstinstallation des Messgeräts im Messnetz und die Beurteilung von dessen Eignung;
- die laufende Qualitätssicherung;
- die Berechnung der Ergebnisse und den Messbericht;
- die Bewertung der Unsicherheit der Messergebnisse unter praktischen Messbedingungen.
Qualité de l'air ambiant - Méthode normalisée pour le mesurage de la concentration en benzène - Partie 3: Prélèvement par pompage automatique avec analyse chromatographique en phase gazeuse sur site
La présente Norme européenne spécifie une méthode de mesure semi-continue pour la détermination de la concentration en benzène dans l’air ambiant par prélèvement automatique et analyse par chromatographie en phase gazeuse. La présente norme décrit les caractéristiques de performance et fixe les critères minimaux requis pour sélectionner un chromatographe en phase gazeuse automatisé approprié (GC) 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 déterminé spécifique de manière à répondre aux exigences de qualité des données 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 massique en benzène présent dans l’air ambiant jusqu’à 50 µg/m3. Cette plage de concentration représente la gamme de certification pour l’essai d’approbation de type.
NOTE 1 D’autres plages peuvent être utilisées selon les niveaux présents dans l’air ambiant.
NOTE 2 Lorsque la norme est utilisée à d’autres fins que la Directive 2008/50/CE, les exigences relatives à la plage et à l’incertitude peuvent ne pas s’appliquer.
La méthode couvre la détermination des concentrations en benzène dans l’air ambiant dans les zones classées comme zones rurales, urbaines de fond, proches d’axes de circulation automobile et influencées par des sources industrielles.
Les résultats sont exprimés en µg/m3 (à 20 °C et 101,3 kPa).
NOTE 3 50 µg/m3 de benzène correspondent à 15,4 nmol/mol de benzène.
La présente norme contient des informations pour différents groupes d’utilisateurs.
Les Articles 5 à 7 et les Annexes C et D contiennent des informations générales relatives aux principes de mesure du benzène à l’aide d’un chromatographe en phase gazeuse automatisé et d’un équipement de prélèvement.
L’Article 8 et l’Annexe E concernent tout particulièrement les entreprises et les laboratoires d’essai qui effectuent des essais d’approbation de type des analyseurs de benzène. 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 mesure de l’analyseur de benzène d’après les résultats de l’essai d’approbation de type.
Les Articles 9 à 11 et les Annexes F à H concernent les réseaux de surveillance effectuant les mesurages pratiques du benzène 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 de routine ;
- le calcul et le compte-rendu des résultats de mesure ;
- l’évaluation de l’incertitude des résultats de mesure sous des conditions de surveillance pratiques.
Zunanji zrak - Standardna metoda za določevanje koncentracije benzena - 3. del: Avtomatsko vzorčenje s črpanjem in določevanje s plinsko kromatografijo na kraju samem (in situ)
Ta del standarda EN 14662 je v skladu s splošno metodologijo, ki je bila izbrana kot podlaga za referenčno metodo Evropske unije za določevanje benzena v zunanjem zraku [1] za namen primerjave rezultatov meritev z mejnimi vrednostmi v enoletnem referenčnem obdobju.
Standard opisuje smernice za meritve z avtomatiziranimi plinskimi kromatografi in homologacijo le-teh. Zaradi uporabe avtomatiziranih instrumentov se struktura tega dela razlikuje od strukture drugih delov, vključno s postopkom izbire primernega avtomatiziranega plinskega kromatografa prek homologacijskih preizkusov.
Opisane so tudi zahteve za uporabo na terenu.
Standard velja za meritve hlapov benzena v zraku v koncentracijah od 0 µg/m3 do 50 µg/m3 (standardizirano na 101,3 kPa in 293 K). Te koncentracije predstavljajo razpon certificiranja za benzen za homologacijski preizkus.
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Außenluft - Referenzverfahren zur Bestimmung von Benzolkonzentrationen - Teil 3: Automatische Probenahme mit einer Pumpe mit gaschromatographischer In-situ-BestimmungAir ambiant - Méthode normalisée de mesurage de la concentration en benzene - Partie 3: Méthode à chromatographie en phase gazeuse automatiqueAmbient air - Standard method for the measurement of benzene concentrations - Part 3: Automated pumped sampling with in situ gas chromatography13.040.20Kakovost okoljskega zrakaAmbient atmospheresICS:Ta slovenski standard je istoveten z:EN 14662-3:2015SIST EN 14662-3:2016en,fr,de01-februar-2016SIST EN 14662-3:2016SLOVENSKI
STANDARDSIST EN 14662-3:20051DGRPHãþD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 14662-3
November
t r s w ICS
s uä r v rä t r Supersedes EN
s v x x tæ uã t r r wEnglish Version
Ambient air æ Standard method for the measurement of benzene concentrations æ Part
uã Automated pumped sampling with in situ gas chromatography Qualité de l 5air ambiant æ Méthode normalisée pour le mesurage de la concentration en benzène æ Partie
uã Prélèvement par pompage automatique avec analyse chromatographique en phase gazeuse sur site
Außenluft æ Messverfahren zur Bestimmung von Benzolkonzentrationen æ Teil
uã Automatische Probenahme mit einer Pumpe und gaschromatographische InæsituæBestimmung This European Standard was approved by CEN on
s y July
t r s wä
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 Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels
t r s w CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s v x x tæ uã t r s w ESIST EN 14662-3:2016
Test of lack of fit . 45 Annex B (informative) Sampling equipment . 47 Annex C (informative)
Components and applications of benzene analysers . 48 Annex D (informative)
Manifold testing equipment . 50 Annex E (normative)
Type approval . 52 Annex F (informative)
Calculation of uncertainty in field operation at the annual limit value . 65 Bibliography . 72
— Clause 8 has been brought in line with other Standards dealing with type approval of gas analysers; — In 9.4 and 9.6, performance requirements have been modified or removed and additional performance criteria and tests have been introduced for repeatability at span level; — In 9.5, formulae have been introduced for software adjustment of the raw analyser signal after calibration; — In Annexes E and F, uncertainty calculations have been modified to be in conformity with EN ISO 14956. 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 14662-3:2016
NOTE 1 When the standard is used for other purposes than for measurements required by Directive 2008/50/EC, the ranges and uncertainty requirements may not apply. The method covers the determination of ambient air concentrations of benzene in zones classified as rural areas, urban-background areas and traffic-orientated locations and locations influenced by industrial sources. The results are expressed in µg/m3 (at 20 °C and 101,3 kPa). NOTE 2 50 µg/m3 of benzene corresponds to 15,4 nmol/mol of benzene. This European Standard contains information for different groups of users. Clauses 5 to 7 and Annexes C and D contain general information about the principles of benzene measurement by automated gas chromatography and sampling equipment. Clause 8 and Annex E are specifically directed towards test houses and laboratories that perform type-approval testing of benzene 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 benzene analyser based on the type-approval test results. Clauses 9 to 11 and Annex F are directed towards monitoring networks performing the practical measurements of benzene 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 14662-3:2016
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 6142, Gas analysis
Preparation of calibration gas mixtures
Gravimetric method (ISO 6142) EN ISO 6143, Gas analysis
Comparison methods for determining and checking the composition of calibration gas mixtures (ISO 6143) EN ISO 6144, Gas analysis
Preparation of calibration gas mixtures
Static volumetric method (ISO 6144) EN ISO 6145-4, Gas analysis
Preparation of calibration gas mixtures using dynamic volumetric methods
Part 4: Continuous syringe injection method (ISO 6145-4) 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 6145-8, Gas analysis
Preparation of calibration gas mixtures using dynamic volumetric methods
Part 8: Diffusion method (ISO 6145-8) EN ISO 6145-9, Gas analysis
Preparation of calibration gas mixtures using dynamic volumetric methods
Part 9: Saturation method (ISO 6145-9) EN ISO 6145-10, Gas analysis
Preparation of calibration gas mixtures using dynamic volumetric methods
Part 10: Permeation method (ISO 6145-10) EN ISO 14956, Air quality
Evaluation of the suitability of a measurement procedure by comparison with a required measurement uncertainty (ISO 14956) 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 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). SIST EN 14662-3:2016
Adjustment of a measuring system should not be confused with calibration, which is a prerequisite for adjustment. Note 3 to entry:
In the context of this European Standard, adjustment is performed on measurement data rather than on the analyser. [SOURCE: JCGM 200:2012 (VIM), Note 3 to entry has been modified, [2]] 3.2 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]] 3.3 analyser analytical instrument 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 3.4 availability of the analyser fraction of the total time period for which valid measuring data of the ambient air concentration is available from an analyser
3.5 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. [SOURCE: JCGM 200:2012 (VIM), modified, 3rd note has been deleted] 3.6 carry-over (memory effect) influence of the previous measurement due to the retention of benzene within the instrument 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 SIST EN 14662-3:2016
In principle, the response of the instruments described in this standard to a zero concentration of benzene should be zero. Consequently, srz may be determined by repeatedly measuring a low concentration of benzene, e.g., 10 % of the level of the annual limit value (see 8.4.4). 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 characterized 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: ISO/IEC Guide 98-3:2008] Note 3 to entry: For the purpose of this 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 independent measurement individual measurement that is not influenced by a previous individual measurement SIST EN 14662-3:2016
[SOURCE: ISO/IEC Guide 98-3:2008] 3.17 interferent component of the air sample, excluding the measured constituent, that affects the output signal 3.18 lack of fit maximum deviation from the linear regression line of the average of a series of measurement results at the same concentration
3.19 limit value level fixed on the basis of scientific knowledge, with the aim of avoiding, preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained within a given period and not to be exceeded once attained [SOURCE: 2008/50/EC [1]] 3.20 long term drift difference between zero or span readings over a determined period of time (e.g. period of unattended operation) 3.21 monitoring station enclosure located in the field in which an analyser has been installed to monitor concentrations of one or more ambient air pollutants in such a way that its performance and operation complies with the prescribed requirements 3.22 parallel measurements measurements from
analysers of same type and model, sampling from one and the same sampling manifold starting at the same time and ending at the same time 3.23 performance characteristic one of the parameters assigned to equipment in order to define its performance SIST EN 14662-3:2016
[SOURCE: ISO/IEC Guide 98-3:2008] 3.34 surrounding temperature temperature of the air directly surrounding the analyser (temperature inside the monitoring station or laboratory) 3.35 type approval decision taken by a competent body that the pattern of an analyser conforms to specified requirements
3.36 type approval test examination of two or more analysers of the same pattern which are submitted by a manufacturer to a competent body including the tests necessary for approval of the pattern 3.37 uncertainty (of measurement) parameter associated with the result of a measurement that characterises the dispersion of the values that could reasonably be attributed to the measurand [SOURCE: ISO/IEC Guide 98-3:2008] 4 Abbreviated terms
AMS automated measuring system MFC mass flow controller PTFE polytetrafluoroethylene QA quality assurance QC quality control SIST EN 14662-3:2016
Two general types of instruments are used. One type samples for only part of the time in each cycle whereas the other type of instrument samples continuously as illustrated in Figures 1 and 2 respectively. Typical cycle times are between 15 min and 1 h.
Figure 1 — Sampling by single trap SIST EN 14662-3:2016
Figure 2 — Sampling by multi-trap Special attention has to be paid to gases that may co-elute with benzene on the chromatographic column selected, such as hydrocarbons with similar boiling points. The final results for reporting shall be expressed in µg/m3 using standard conversion factors (see Clause 10). 5.3 Type approval test The type approval test is based on the evaluation of performance characteristics determined under a prescribed series of tests. In this European Standard, test procedures are described for the determination of the actual values of the performance characteristics for at least two analysers in a laboratory and the same analysers in the field operated in parallel in both cases. The type approval laboratory tests shall not include the sampling inlet or sampling manifold and external data acquisition system, but shall include analyser sampling line and filter. The type approval field test may include a sampling inlet and a sampling manifold. However, the influence of these components on the test results shall be minimized by proper maintenance. A competent body shall perform these tests. The evaluation for type approval of an analyser is based on the calculation of the expanded uncertainty in the measuring result based on the numerical values of the tested performance characteristics and compared with a prescribed maximum uncertainty. The type approval of an analyser and subsequent QA and QC procedures provide evidence that the defined requirements concerning data quality laid out in Annex I of Directive 2008/50/EC [1] can be satisfied. Appropriate experimental evidence shall be provided by: — type approval tests performed under conditions of intended use of the specified method of measurement, and — calculation of expanded uncertainty of results of measurement by reference to ISO/IEC Guide 98-3:2008. SIST EN 14662-3:2016
In Annex B, different arrangements of the sampling equipment are schematically presented. 6.2 Sampling location The location where the ambient air shall be sampled and analysed is not specified as this depends strongly on the category of a monitoring station (such as measurements in, e.g. a rural area or urban background area). Guidance and criteria on sampling points on a micro scale are given in Annex III of Directive 2008/50/EC. 6.3 Sampling system 6.3.1 Construction The sampling system shall include a sampling inlet and may include the following components: — a sampling line or manifold; — a particle filter placed between the sampling line or manifold and the analyser; — a sampling pump in case a sampling manifold is used. The sample inlet shall be constructed in such a way that ingress of rainwater into the sampling line or manifold is prevented. The sampling line or manifold shall be as short as practical to minimize the residence time (i.e. within 6 s, see Annex D). In the case where a sampling manifold is used, an additional pump is necessary with sufficient capacity to fulfil the sampling requirements stated in the previous subclauses (see also 6.5 and Annex D).
The material of the sample inlet as well as the sampling line or manifold can influence the composition of the sample. These shall be chemically inert to benzene.
NOTE In practice, the best materials to be used are borosilicate glass and stainless steel. SIST EN 14662-3:2016
¶ 1,0 %. 6.3.2 Particle filter A particle filter shall be used to protect the analyser. The filter shall retain all particles likely to alter the performance of the analyser. The material of the filter and its housing shall be chemically inert to benzene. NOTE 1 A pore size of the filter of 5 µm usually fulfils this requirement. NOTE 2 Suitable materials for the filter housing are for example PTFE, stainless steel, or borosilicate glass.
The filter shall be changed periodically depending on the dust loading at the sampling site (as indicated in 9.7). The filter housing shall be cleaned at least every year. Overloading of the filter may cause loss of benzene by adsorption on the particle matter and may increase the pressure drop in the sampling line. 6.3.3 Loss of benzene Depending on the location of the particulate filter, the sampling system can be contaminated by deposition of dust. This can induce losses of benzene. The sampling system shall be cleaned (as stated in 9.4.1) with a frequency which is dependent on the site-specific conditions. 6.3.4 Conditioning The sampling system and the particle filter shall be conditioned (at initial installation and after each cleaning) to avoid temporary decreases in the measured benzene concentrations by sampling ambient air for a period of at least 30 min at the nominal sample flow rate. These conditioning periods shall not be included in the calculation of the availability of the analyser during the type approval test (8.5.7). Conditioning may also be done in the laboratory before installing. NOTE Conditioning during field operation is considered a part of normal maintenance. Consequently, the concentrations measured during conditioning need not be included in the calculation of data capture, and annual averages. 6.4 Control and regulation of sample volume The volume of air sampled into the sampling trap shall be maintained within the specifications of the manufacturer of the analyser.
6.5 Sampling pump for the manifold When a sampling manifold is used, a pump is necessary for sampling ambient air and suction of the sampled air through the sampling manifold. The inlet of the sampling pump (or blower) for the sampling manifold shall be located at the end of the sampling manifold (see Annex D). The sampling pump or fan shall have sufficient rating to ensure that all analysers connected to the manifold are supplied with the required amount of air. To verify functioning of this pump, it is recommended to install a flow alarm system. An example of a sampling manifold is given in Annex D.
The influence of the pressure drop induced by the manifold sampling pump on the measured concentration shall be
¶ 1,0 %.(see 9.6.3.1) SIST EN 14662-3:2016
7.2 Sampling trap A typical sampling trap is made of stainless steel or borosilicate glass. It is packed with a sorbent or series of sorbents capable of quantitatively retaining benzene in a minimum volume of air sampled needed to measure concentrations of benzene at or below 10 % of the level of the annual limit value. A sorbent particle size of 0,18 mm to 0,25 mm (60 mesh to 80 mesh) is recommended. The sampling trap will degrade over time due to its repetitive heating and cooling, and shall be changed in accordance with the manufacturer’s recommendations. 7.3 Sampling device The sampling device used may vary between instruments but shall be able to deliver a known sample volume at standard conditions of temperature and pressure. 7.4 Thermal desorption unit Depending on the instrument used the thermal desorption unit may be suitable for single- or two-stage desorption of the benzene from the sampling trap. Desorption is effected by heating the trap within a short time period whilst passing a flow of carrier gas (typically nitrogen). Temperature, gas flow rate and time need to be sufficient to quantitatively transfer the trapped benzene to a secondary trap, a pre-column or the analytical column, depending on the instrument. When a secondary trap or pre-column are used similar requirements hold for desorption of benzene from these traps. In addition, the secondary desorption shall be such that the chromatographic resolution of benzene from (potential) interferents is optimized. 7.5 Separation unit The separation unit consists of an analytical (separation) column and an oven used for heating the column to effect the separation of benzene from (potential) interferents within a period sufficient to allow its quantification at concentrations equal to or lower than 10 % of the annual limit value. NOTE Effective separation and quantification may require the application of temperature programming. This will affect the minimum cycle time between measurements. 7.6 Detector The detector shall be able to allow quantification of benzene at concentrations equal to or lower than 10 % of the annual limit value. Detectors mostly used are flame ionization and photo-ionisation detectors.
NOTE The latter does not require additional gases for its operation, but is prone to a higher response drift and requires more frequent maintenance. SIST EN 14662-3:2016
The determination of the concentration of benzene in ambient air has to fulfil the requirement of a maximum uncertainty in the measured values, which is prescribed by Annex I of Directive 2008/50/EC (25 % for fixed measurements or 30 % for indicative measurements). In order to achieve an uncertainty less than (or equal to) this required uncertainty, the analyser has to fulfil all the criteria for a number of performance characteristics, which are given in this standard. The values of the selected performance characteristics shall be evaluated by means of laboratory and field tests. By combining the values of the selected performance characteristics in the expanded uncertainty calculation a judgement can be made whether or not the analyser meets the criterion of maximum uncertainty prescribed by Annex I of Directive 2008/50/EC (25 % for fixed measurements or 30 % for indicative measurements). This process of assessment (type approval test) of the values of the performance characteristics comprises laboratory and field tests and the calculation of the expanded uncertainty. At least two analysers of the same type shall be tested in the laboratory. The same analysers shall be tested during the field test. All analysers tested shall pass both tests. The type approval procedure shall fulfil the certification requirements laid down in European Standards EN 15267-1 and EN 15267-2. A competent body shall perform the type approval tests. The type approval shall be awarded by or on behalf of the competent authority. The competent body performing the required tests shall be able to demonstrate that it works in compliance with the requirements of internationally accepted standards for test laboratories. NOTE 1 EN ISO/IEC 17025 is a harmonized internationally accepted standard. NOTE 2 An accreditation by a member body of the European co-operation for Accreditation to EN ISO/IEC 17025 is a demonstration of compliance. EN 15267-1 specifies the general principles of the product certification of automated measuring systems (AMS) for monitoring emissions from stationary sources and ambient air quality. This product certification consists of the following sequential stages: — performance testing of an AMS; — initial assessment of the AMS manufacturer’s quality management system; — certification; — post-certification product-surveillance. SIST EN 14662-3:2016
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