SIST EN 15058:2006
(Main)Stationary source emissions - Determination of the mass concentration of carbon monoxide (CO) - Reference method: Non-dispersive infrared spectrometry
Stationary source emissions - Determination of the mass concentration of carbon monoxide (CO) - Reference method: Non-dispersive infrared spectrometry
This European Standard specifies the Standard Reference Method (SRM) for sampling, and determining car-bon monoxide content in ducts and stacks emitting to atmosphere. It describes the Non Dispersive Infra-Red (NDIR) analytical technique, including the sampling system and sample gas conditioning system, to determine CO in flue gases. This European Standard is the reference method for periodic monitoring and for calibration or control of Automatic Measuring Systems (AMS) permanently installed on a stack, for regulatory purposes or other purposes. To be used as the SRM, it is necessary to demonstrate that the performance characteristics of the method are lower than the performance criteria defined in this European standard and that the overall uncertainty of the method is less than ± 6 % relative at the daily Emission Limit Value (ELV).
NOTE When the NDIR method is used as an AMS, refer to EN 14181 and other relevant standards provided by CEN TC 264.
It is necessary for anybody who would like to use an Alternative Method instead of this Standard Reference Method to work out the demonstration of the equivalence according to the Technical Specification TS 14793, providing that his capability to carry out this demonstration is officially recognised by his national accreditation body or law.
This Standard Reference Method has been evaluated during field tests on waste incineration, co-incineration installations and large combustion plants. It has been validated for CO concentrations with sampling periods of 30 min in the range of 0 mg/m3 to 400 mg/m3 for large combustion plants and 0 mg/m3 – 740 mg/m3 for waste and co-incineration. For waste incineration plants, Council Directive 2000/76/EC lays down emission values which are expressed in mg/m3, on dry basis at a specified value of O2 and at reference conditions of 273 K and 101,3 kPa.
Emissionen aus stationären Quellen - Bestimmung der Massenkonzentration von Kohlenmonoxid (CO) - Referenzverfahren: Nicht-dispersive Infrarotspektrometrie
Diese Europäische Norm legt das Standardreferenzverfahren (SRM) zur Probenahme und zur Bestimmung des Gehalts von Kohlenmonoxid in Leitungen und Kaminen, die in die Atmosphäre emittieren, fest. Sie beschreibt das NDIR-Analysenverfahren, einschließlich der Einrichtungen zur Probenahme und zur Probengaskonditionierung. Dieses Verfahren ist das Referenzverfahren für die periodische Überwachung, Kalibrierung und Kontrolle von im Abgaskamin fest installierten automatischen Messeinrichtungen (AMS), die für gesetzlich geregelte und andere Messungen eingesetzt werden. Wenn das Verfahren als Standardreferenzverfahren angewendet wird, ist zu belegen, dass die Leistungskenngrößen niedriger als die in dieser Europäischen Norm festgelegten Leistungskriterien sind und dass die Gesamtunsicherheit des Verfahrens kleiner als ± 6 % (relativ) beim 1-Tages-Emissionsgrenzwert (ELV) ist.
ANMERKUNG Wenn das NDIR-Verfahren in automatischen Messeinrichtungen angewendet wird, sind EN 14181 und andere relevante Normen des CEN TC 264 zu beachten.
Sollte anstelle dieses Standardreferenzverfahrens ein anderes Verfahren eingesetzt werden, ist dessen Äquivalenz nach der Technischen Spezifikation CEN/TS 14793 nachzuweisen, wobei der Anwender über eine entsprechende Anerkennung durch die nationale Akkreditierungsstelle oder entsprechend einer gesetzlichen Regelung verfügen muss.
Dieses Referenzverfahren wurde in Feldversuchen an Abfallverbrennungs- und Mitverbrennungsanlagen sowie Großfeuerungsanlagen für Probenahmezeiten von 30 min und CO-Konzentrationen von 0 mg/m3 bis 400 mg/m3 (Großfeuerungsanlagen) und 0 mg/m3 bis 740 mg/m3 (Abfallverbrennungs- und Mitverbrennungsanlagen) validiert. Für Abfallverbrennungsanlagen legt die Richtlinie des Rates 2000/76/EG Emissionswerte fest, die in mg/m3 angegeben sind, bezogen auf trockenes Gas bei festgelegter O2-Bezugskonzentration und bezogen auf die Normbedingungen 273 K und 101,3 kPa.
Emissions de sources fixes - Détermination de la concentration massique en monoxyde de carbone (CO) - Méthode de référence : spectrométrie infrarouge non dispersive
La présente Norme européenne spécifie la méthode de référence normalisée (SRM, Standard Reference Me-thod)
pour le prélevement et la détermination de la teneur en monoxyde de carbone des émissions atmosphé-riques
provenant des conduits et des cheminées. Elle décrit la technique d’analyse par absorption infrarouge
non dispersive (NDIR) ainsi que les systemes de prélevement et de conditionnement de l’échantillon de gaz,
permettant de déterminer la teneur en CO dans les effluents gazeux. La présente Norme européenne est la
méthode de référence en matiere de surveillance périodique et d’étalonnage ou de contrôle des systemes
automatiques de mesurage (AMS, Automatic Measuring Systems) installés a demeure sur une cheminée, a
des fins réglementaires ou a d’autres fins. Pour qu’une méthode puisse etre utilisée comme méthode de réfé-rence
normalisée (SRM), il est nécessaire de démontrer que ses caractéristiques de performance sont infé-rieures
aux criteres de performance définis dans la présente Norme européenne et que l’incertitude globale
est inférieure a ± 6 % relatifs a la valeur limite d’émission journaliere (VLE).
NOTE Lorsque la méthode NDIR est utilisée comme AMS, consulter l’EN 14181 et les autres normes applicables
élaborées par le CEN TC 264.
Toute personne souhaitant utiliser une autre méthode que la présente Méthode de référence normalisée, de-vra
démontrer son équivalence selon la spécification technique TS 14793, et que sa capacité pour réaliser
cette démonstration est reconnue officiellement par son organisme d’accréditation national ou la loi en vi gueur.
Emisije nepremičnih virov – Določevanje masne koncentracije ogljikovega monoksida (CO) – Referenčna metoda: nedisperzivna infrardeča spektrometrija
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.NRYHJDWURPHWULMDEmissionen aus stationären Quellen - Bestimmung der Massenkonzentration von Kohlenmonoxid (CO) - Referenzverfahren:
Nicht-dispersive InfrarotspektrometrieEmissions de sources fixes - Détermination de la concentration massique en monoxyde de carbone (CO) - Méthode de référence : spectrométrie infrarouge non dispersiveStationary source emissions - Determination of the mass concentration of carbon monoxide (CO) - Reference method: Non-dispersive infrared spectrometry13.040.40Stationary source emissionsICS:Ta slovenski standard je istoveten z:EN 15058:2006SIST EN 15058:2006en,fr,de01-julij-2006SIST EN 15058:2006SLOVENSKI
STANDARD
SIST EN 15058:2006
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15058May 2006ICS 13.040.40 English VersionStationary source emissions - Determination of the massconcentration of carbon monoxide (CO) - Reference method:Non-dispersive infrared spectrometryEmissions de sources fixes - Détermination de laconcentration massique en monoxyde de carbone (CO) -Méthode de référence : spectrométrie infrarouge nondispersiveEmissionen aus stationären Quellen - Bestimmung derMassenkonzentration von Kohlenmonoxid (CO) -Referenzverfahren:
Nicht-dispersive InfrarotspektrometrieThis European Standard was approved by CEN on 20 April 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15058:2006: ESIST EN 15058:2006
EN 15058:2006 (E) 2 Contents Page Foreword.3 1 Scope.4 2 Normative references.4 3 Terms and definitions.4 4 Principle.9 4.1 General.9 4.2 Measuring principle.9 5 Sampling system.10 5.1 General.10 5.2 Sampling system.10 6 Analyser equipment.12 6.1 General.12 6.2 Pressure and temperature effects.12 6.3 Sampling pump for the analyser.12 6.4 Interferences due to infrared absorbing gases.12 7 Determination of the characteristics of the method: analyser, sampling and conditioning line.13 7.1 General.13 7.2 Relevant performance characteristics of the method and performance criteria.13 7.3 Establishment of the uncertainty budget.14 8 Field operation.15 8.1 Sampling location.15 8.2 Sampling point.15 8.3 Choice of the measuring system.16 8.4 Setting of the analyser on site.16 9 Ongoing quality control.17 9.1 Introduction.17 9.2 Frequency of checks.17 10 Expression of results.18 11 Evaluation of the method in the field.19 12 Equivalency with an alternative method.19 13 Test report.20 Annex A (informative)
Schematics of non-dispersive infrared spectrometer.21 Annex B (informative)
Example of assessment of compliance of non-dispersive infrared method for CO with requirements on emission measurements.23 Annex C (informative)
Evaluation of the method in the field.35 Annex D (informative)
Procedure of correction of data from drift effect.39 Annex E (informative)
Relationship with EU Directives.40 Bibliography.41
SIST EN 15058:2006
EN 15058:2006 (E) 3 Foreword This document (EN 15058:2006) 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 November 2006, and conflicting national standards shall be withdrawn at the latest by November 2006. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 15058:2006
EN 15058:2006 (E) 4 1 Scope This European Standard specifies the Standard Reference Method (SRM) for sampling, and determining car-bon monoxide content in ducts and stacks emitting to atmosphere. It describes the Non Dispersive Infra-Red (NDIR) analytical technique, including the sampling system and sample gas conditioning system, to determine CO in flue gases. This European Standard is the reference method for periodic monitoring and for calibration or control of Automatic Measuring Systems (AMS) permanently installed on a stack, for regulatory purposes or other purposes. To be used as the SRM, it is necessary to demonstrate that the performance characteristics of the method are lower than the performance criteria defined in this European standard and that the overall uncertainty of the method is less than ± 6 % relative at the daily Emission Limit Value (ELV). NOTE When the NDIR method is used as an AMS, refer to EN 14181 and other relevant standards provided by CEN TC 264. It is necessary for anybody who would like to use an Alternative Method instead of this Standard Reference Method to work out the demonstration of the equivalence according to the Technical Specification TS 14793, providing that his capability to carry out this demonstration is officially recognised by his national accreditation body or law. This Standard Reference Method has been evaluated during field tests on waste incineration, co-incineration installations and large combustion plants. It has been validated for CO concentrations with sampling periods of 30 min in the range of 0 mg/m3 to 400 mg/m3 for large combustion plants and 0 mg/m3 – 740 mg/m3 for waste and co-incineration. For waste incineration plants, Council Directive 2000/76/EC lays down emission values which are expressed in mg/m3, on dry basis at a specified value of O2 and at reference conditions of 273 K and 101,3 kPa. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer-ences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ENV 13005, Guide to the expression of uncertainty in measurement. CEN/TS 14793: Stationary source emission - Intralaboratory validation procedure for an alternative method compared to a reference method. EN ISO 14956, Air Quality – Evaluation of the suitability of a measurement procedure by comparison with a required measurement uncertainty (ISO 14956:2002). ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results – Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. ISO 5725-6:1994, Accuracy (trueness and precision) of measurement methods and results - Part 6: Use in practice of accuracy values. VIM 1994, International vocabulary of basic and general terms in metrology. 3 Terms and definitions For the purposes of this document the following terms and definitions apply. SIST EN 15058:2006
EN 15058:2006 (E) 5 3.1 adjustment (of a measuring system) operation of bringing a measuring system into a state of performance suitable for its use [VIM 4.30] 3.2 ambient temperature temperature of the air around the measuring system 3.3 automatic measuring system (AMS) measuring system permanently installed on site for continuous monitoring of emissions NOTE 1 An AMS is a method which is traceable to a reference method. NOTE 2 Apart from the analyser, an AMS includes facilities for taking samples (e.g. probe, sample gas lines, flow me-ters, regulators, delivery pumps) and for sample conditioning (e.g.dust filter, moisture removal devices, converters, dilut-ers). This definition also includes testing and adjusting devices that are required for regular functional checks. 3.4 calibration statistical relationship between values of the measurand indicated by the 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 sampling plane NOTE The result of calibration permits to establish the relationship between the values of the SRM and the AMS (calibration function). 3.5 drift difference between two zero (zero drift) or span readings (span drift) at the beginning and at the end of a measuring period 3.6 emission limit value (ELV) emission limit value according to EU Directives on the basis of 30 min, 1 hour or 1 day 3.7 influence quantity quantity that is not the measurand but that affects the result of the measurement [adapted VIM 2.7] EXAMPLES ambient temperature; atmospheric pressure; presence of interfering gases in the flue gas matrix; pressure of the gas sample. SIST EN 15058:2006
EN 15058:2006 (E) 6 3.8 interference negative or positive effect upon the response of the measuring system, due to a component of the sample that is not the measurand 3.9 lack of fit systematic deviation within the range of application between the measurement result obtained by applying the calibration function to the observed response of the measuring system measuring test gases and the corre-sponding accepted value of such test gases NOTE 1 Lack of fit may be a function of the measurement result. NOTE 2 The expression “lack of fit” is often replaced in everyday language by “linearity” or “deviation from linearity”. 3.10 measurand particular quantity subject to measurement [VIM 2.6] 3.11 measuring system complete set of measuring instruments and other equipment assembled to carry out specified measurements [VIM 4.5] 3.12 performance characteristic one of the quantities (described by values, tolerances, range…) assigned to equipment in order to define its performance 3.13 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 Repeatability conditions include: same measurement procedure; same laboratory; same measuring system, used under the same conditions; same location; repetition over a short period of time. NOTE 2 Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results. In this European Standard the repeatability is expressed as a value with a level of confidence of 95 %. [VIM 3.6] 3.14 repeatability in the field closeness of the agreement between the results of simultaneous measurements of the same measurand car-ried out with two sets of equipment under the same conditions of measurement SIST EN 15058:2006
EN 15058:2006 (E) 7 NOTE 1 These conditions include: same measurement procedure; two sets of equipment, the performance of which fulfils 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). NOTE 2 Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results. In this European Standard the repeatability under field conditions is expressed as a value with a level of confi-dence of 95 %. 3.15 reproducibility in the field closeness of the agreement between the results of simultaneous measurements of the same measurand car-ried out using several sets of equipment under the same conditions of measurement NOTE 1 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 Reproducibility may be expressed quantitatively in terms of the dispersion characteristics of the results. In this European Standard the reproducibility under field conditions is expressed as a value with a level of con-fidence of 95 %. 3.16 residence time in the measuring system time period for the sampled gas to be transported from the inlet of the probe to the inlet of the measurement cell 3.17 response time time interval between the instant when a stimulus is subjected to a specified abrupt change and the instant when the response reaches and remains within specified limits around its final steady value NOTE By convention time taken for the output signal to pass from 0 % to 90 % of the final change. [VIM 5.17] 3.18 sampling location specific area close to the sampling plane where the measurement devices are set up SIST EN 15058:2006
EN 15058:2006 (E) 8 3.19 sampling plane plane normal to the centreline of the duct at the sampling position [EN 13284-1] 3.20 sampling point specific position on a sampling line at which a sample is extracted [EN 13284-1] 3.21 span gas test gas used to adjust and check a specific point on the response line of the measuring system NOTE This concentration is often chosen around 80 % of the upper limit of the range or around the emission limit value. 3.22 standard reference method (SRM) measurement method recognised by experts and taken as a reference by convention, which gives, or is pre-sumed to give, the accepted reference value of the concentration of the measurand (3.10) to be measured 3.23 uncertainty parameter associated with the result of a measurement, that characterises the dispersion of the values that could reasonably be attributed to the measurand 3.23.1 standard uncertainty u uncertainty of the result of a measurement expressed as a standard deviation u 3.23.2 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 In this European Standard, the expanded uncertainty is calculated with a coverage factor of k = 2, and with a level of confidence of 95 %. 3.23.3 combined uncertainty uc standard uncertainty uc attached to the measurement result calculated by combination of several standard uncertainties according to GUM. 3.23.4 overall uncertainty Uc expanded combined standard uncertainty attached to the measurement result calculated according to GUM Uc = k × uc
SIST EN 15058:2006
EN 15058:2006 (E) 9 3.24 uncertainty budget calculation table combining all the sources of uncertainty according to EN ISO 14956 or ENV 13005 in order to calculate the overall uncertainty of the method at a specified value 4 Principle 4.1 General This European standard describes the reference method for sampling, and determining the carbon monoxide (CO) concentration in ducts and stacks emitting to atmosphere by means of an automatic analyser using Non Dispersive Infra-Red (NDIR) absorption principle. The specific components and the requirements for the sam-pling system and the NDIR analyser are described in Clause 6. A number of performance characteristics with associated minimum performance criteria are given for the analyser. These performance characteristics and the overall uncertainty of the method shall meet the performance criteria given in this European Standard. Re-quirements and recommendations for quality assurance and quality control are given for measurements in the field (see Table 1 in 7.2). 4.2 Measuring principle CO concentration is measured with use of non-dispersive infrared methods. The attenuation of infrared light passing through a sample cell is a measure of the concentration of CO in the cell, according to the Lambert-Beer law. Not only CO but also most hetero-atomic molecules absorb infrared light, in particular water and CO2 have broad bands that can interfere with the measurement of CO. Different technical solutions have been developed to suppress cross-sensitivity, instability and drift in order to design automatic monitoring systems with acceptable properties. For instance: measuring IR absorption of a specific wavelength (4,7 µm for CO); dual-cell monitors, using a reference cell filled with clean air (compensation for drift); gas filter correlation, “measuring” over a range of wavelengths. Special attention shall be paid to infrared radiation absorbing gases such as water vapour, carbon dioxide, nitrous oxide and hydrocarbons. NDIR analysers are combined with an extractive sampling system and a gas conditioning system. A represen-tative sample of gas is taken from the stack with a sampling probe and conveyed to the analyser through the sampling line and gas conditioning system. The values from the analyser are recorded and/or stored by means of electronic data processing. The concentration of carbon monoxide is measured in volume/volume units (if the analyser is calibrated using a volume/volume standard). The final results for reporting are expressed in milligrams per cubic meter using standard conversion factors (see Clause 10). SIST EN 15058:2006
EN 15058:2006 (E) 10 5 Sampling system 5.1 General A representative volume (see 8.2) is extracted from the flue gas for a fixed period of time at a controlled flow rate. The sampling system consists of: sampling probe; filter; sampling line; conditioning system. A filter removes the dust in the sampled volume before the sample is conditioned and passes to the analyser. Two different sampling and conditioning configurations can be used in order to avoid the water condensation in the measuring system. These configurations are: Configuration 1: removal of water vapour by condensation using a cooling system; Configuration 2: removal of water vapour through elimination using a permeation drier. It is important that all parts of the sampling equipment upstream of the analyser are made of materials that do not react with or absorb CO. The temperature of its components coming into contact with the gas shall be maintained at a sufficiently high temperature to avoid any condensation and alter the gas composition. Conditions and layout of the sampling equipment contribute to the overall uncertainty of the measurement. In order to minimise this contribution to the overall measurement uncertainty, performance criteria for the sam-pling equipment and sampling conditions are given in 5.2 and 7.2. 5.2 Sampling system 5.2.1 Sampling probe In order to reach the representative measurement point(s) of the sampling 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. The procedure described in 8.2 shall be used when a lack of homogeneity in the flue gas is suspected. 5.2.2 Filter The filter shall be made of an inert material (e. g. ceramic or sinter metal filter with an appropriate pore size). It shall be heated above the sample dew point temperature. The particle filter shall be changed or cleaned peri-odically depending on the dust loading at the sampling site. NOTE Overloading of the particle filter may increase the pressure drop in the sampling line. SIST EN 15058:2006
EN 15058:2006 (E) 11 5.2.3 Sampling line The sampling line shall be heated up to the conditioning system. It shall be made of a suitable corrosion resis-tant material (e. g. stainless steel, borosilicate glass, ceramic or titanium could be used; PTFE is only suitable for flue gas temperature lower than 200 °C). NOTE Excessive temperature should be avoided because it might alter the flue gas characteristics. 5.2.4 Conditioning system 5.2.4.1 Sample cooler (configuration 1) A dew-point temperature of 4 °C shall not be exceeded at the outlet of the sample cooler. NOTE The concentrations, provided by this sampling configuration, are considered to be given on dry basis. How-ever, the results may be corrected for the remaining water vapour (refer to the table of Annex A in EN 14790:2005). 5.2.4.2 Permeation drier (configuration 2) The permeation drier is used before the gas enters the analyser in order to separate water vapour from the flue gas. A dew-point temperature of 4 °C shall not be exceeded at the outlet of the permeation drier. NOTE The concentrations, provided by this sampling configuration, are considered to be given on dry basis. How-ever, the results may be corrected for the remaining water vapour (refer to the table of Annex A in EN 14790:2005). 5.2.5 Sample pump The sample pump shall be capable of operating to the specified flow requirements of the manufacturer of the analyser and pressure conditions required for the sample cell. The pump shall be resistant to corrosion. An external pump shall be consistent with the requirements of the analyser to which it is connected. 5.2.6 Secondary filter The secondary filter is used to separate fine dust, with a pore size less than 5 µm. For example it may be made of glass-fibre, sintered ceramic, stainless steel or PTFE-fibre. 5.2.7 Flow controller and flow meter This apparatus sets the required flow. A corrosion resistant material shall be used. The sample flow rate into the analyser shall be maintained within the analyser manufacturer’s requirements. A controlled pressure drop across restrictors is usually employed to maintain flow rate control into the NDIR analyser. NOTE No additional flow controller or flow meter is necessary when they are part of the analyser itself. SIST EN 15058:2006
EN 15058:2006 (E) 12 6 Analyser equipment 6.1 General The main parts of the analyser are typically: source of infrared radiation; optics to focus the radiation through the measuring cell to the infrared detector; way of modulating the infrared beam; means to select a suitable wavelength or wavelengths to measure the gas;
measuring cell that the sample gas enters. There may be a reference cell in some designs;
infrared detector; amplifier and signal processing system to give an electrical output proportional to the CO concentration. The standard of construction and vibration/corrosion resistance shall be suited to industrial environments and to the composition of the flue gas. In Annex A schematic diagrams are given of two types of non-dispersive infrared analysers. 6.2 Pressure and temperature effects The output signal of the analyser is proportional to the density of CO (number of CO molecules) present in the absorption cell and depends on the absolute pressure and temperature in the absorption cell. The effects of variations of pressure and temperature in the absorption cell should be taken into account by the manufac-turer. 6.3 Sampling pump for the analyser The sampling pump can be separate or part of the analyser. In any case, it shall be capable of operating within the specified flow requirements of the manufacturer of the analyser and pressure conditions required for the NDIR absorption cell. 6.4 Interferences due to infrared absorbing gases 6.4.1 General As various gases absorb infrared radiation, interference from these gases can occur when their infrared ab-sorption bands coincide or overlap the CO infrared absorption bands. The degree of interference varies among individual NDIR analysers. In general, gas correlation spectrophotometers are less sensitive to the influence of interferents. 6.4.2 Water vapour The primary interferent is water vapour. However water vapour interference should be minimised by using sampling and conditioning configuration 1 or 2. SIST EN 15058:2006
EN 15058:2006 (E) 13 6.4.3 Other interferents Other known interferents are carbon dioxide, hydrocarbons and N2O. Knowledge of the gas composition and the cross sensitivity of the analyser is useful to ensure that none of the compounds interfere with the meas-urement. 7 Determination of the characteristics of the method: analyser, sampling and conditioning line 7.1 General When this European standard is used as a reference method, the user shall demonstrate that: performance characteristics of the method given in Table 1 shall be equal or better than the associated performance criteria; and overall uncertainty calculated by combining values of standard uncertainties associated to the perform-ance characteristics given in Table 1 is less than 6 % at the daily emission limit value, on dry basis and before correction to the specified value of O2. The values of the selected performance characteristics shall be evaluated by means of a laboratory test and a field test. An experienced laboratory recognised by the competent authority shall perform the laboratory tests. The user shall perform the f
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