SIST EN 61207-6:2015
(Main)Expression of Performance of gas analyzers- Part 6: Photometric analyzers (IEC 61207-6:2014)
Expression of Performance of gas analyzers- Part 6: Photometric analyzers (IEC 61207-6:2014)
This part of IEC 61207 applies to all aspects of analyzers using photometric techniques for the measurement of concentration of one or more components in a mixture of gases or vapors. It should be used in conjunction with IEC 61207-1.
For photometric analyzers utilizing tuneable semiconductor laser absorption spectroscopy (TSLAS) for gas measurements, IEC 61207-7 should also be referred to.
This part of IEC 61207 applies to analyzers using non-dispersive and dispersive wavelength selection and using absorption, emission, wavelength derivative or scattering techniques. It applies to analyzers which receive either a conditioned or unconditioned sample of gas either under vacuum, at ambient pressure or pressurized.
It applies to analyzers which measure gas concentrations directly within the sample gas.
The object of this part is:
– to specify the terminology and definitions related to the functional performance of gas analyzers, utilizing a photometric analyzer, for the continuous measurement of gas or vapor concentration in a source gas;
– to unify methods used in making and verifying statements on the functional performance of such analyzers;
– to specify what tests should be performed to determine the functional performance and how such tests should be carried out;
– to provide basic documents to support the application of standards of quality assurance ISO 9001
Angabe zum Betriebsverhalten von Gasanalysatoren - Teil 6: Fotometrische Analysatoren (IEC 61207-6:2014)
Expression des performances des analyseurs de gaz - Partie 6: Analyseurs photométriques (IEC 61207-6:2014)
L'IEC 61207-6:2014 s'applique à tous les aspects des analyseurs utilisant les techniques photométriques pour mesurer la concentration d'un ou de plusieurs composants dans un mélange de gaz ou de vapeurs. Il convient de l'utiliser avec l'IEC 61207-1. Elle spécifie:
- la terminologie et les définitions relatives aux performances fonctionnelles des analyseurs de gaz utilisant un analyseur photométrique, pour la mesure en continu de la concentration de gaz ou de vapeur dans un gaz source;
- elle unifie les méthodes utilisées en fournissant et en vérifiant les indications relatives aux performances fonctionnelles de ces analyseurs;
- elle spécifie les essais qu'il convient d'effectuer pour déterminer les performances fonctionnelles et la manière dont il convient d'effectuer ces essais et elle stipule les documents de base pour étayer l'usage des normes d'assurance de la qualité ISO 9001. Cette deuxième édition annule et remplace la première édition parue en 1994 et constitue une révision technique. Les modifications sont:
- Toutes les références (normatives et informatives) ont été mises à jour, retirées ou ajoutées comme il convient.
- Tous les termes et définitions en rapport avec le document ont été mis à jour le cas échéant.
- De nouvelles définitions ont été ajoutées pour les équipements et mesures photométriques génériques.
- Toutes les références aux "erreurs" ont été remplacées par le terme "incertitudes" et les définitions ont été mises à jour comme il convient.
- Les Figures A.1 et A.2 ont été mises à jour.
Prikaz lastnosti analizatorjev plina - 6. del: Fotometrični analizatorji (IEC 61207-6:2014)
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Angabe zum Betriebsverhalten von Gasanalysatoren - Teil 6: Fotometrische Analysatoren (IEC 61207-6:2014)Expression des performances des analyseurs de gaz - Partie 6: Analyseurs photométriques (IEC 61207-6:2014)Expression of Performance of gas analyzers- Part 6: Photometric analyzers (IEC 61207-6:2014)71.040.40Kemijska analizaChemical analysis19.080SUHVNXãDQMHElectrical and electronic testingICS:Ta slovenski standard je istoveten z:EN 61207-6:2015SIST EN 61207-6:2015en01-junij-2015SIST EN 61207-6:2015SLOVENSKI
STANDARD
SIST EN 61207-6:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 61207-6
January 2015 ICS 19.080; 71.040.40
Supersedes
EN 61207-6:1994
English Version
Expression of performance of gas analyzers -
Part 6:Photometric analyzers (IEC 61207-6:2014)
Expression des performances des analyseurs de gaz - Partie 6: Analyseurs photométriques (IEC 61207-6:2014)
Angabe zum Betriebsverhalten von Gasanalysatoren -
Teil 6: Fotometrische Analysatoren (IEC 61207-6:2014) This European Standard was approved by CENELEC on 2014-12-30. CENELEC 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 CENELEC 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 CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue Marnix 17,
B-1000 Brussels © 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61207-6:2015 E SIST EN 61207-6:2015
EN 61207-6:2015 - 2 - Foreword The text of document 65B/947/FDIS, future edition 2 of IEC 61207-6, prepared by SC 65B "Measurement and control devices", of IEC/TC 65 "Industrial-process measurement, control and automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 61207-6:2015. The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2015-09-30 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2017-12-30
This document supersedes EN 61207-6:1994. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 61207-6:2014 was approved by CENELEC as a European Standard without any modification. SIST EN 61207-6:2015
- 3 - EN 61207-6:2015 Annex ZA (normative)
Normative references to international publications with their corresponding European publications 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. NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu.
Publication Year Title EN/HD Year IEC 60079-29-1
-
Explosive atmospheres - Part 29-1: Gas detectors - Performance requirements of detectors for flammable gases EN 60079-29-1 -
IEC 60079-29-4
-
Explosive atmospheres - Part 29-4: Gas detectors - Performance requirements of open path detectors for flammable gases EN 60079-29-4 -
IEC 60654 series
Operating conditions for industrial-process measurement and control equipment EN 60654 series
IEC 61207-1 -
Expression of performance of gas analyzers - Part 1: General EN 61207-1 -
IEC 61207-7 -
Expression of performance of gas analyzers - Part 7: Tuneable semiconductor laser gas analyzers EN 61207-7 -
ISO 9001 -
Quality management systems - Requirements EN ISO 9001 -
SIST EN 61207-6:2015
SIST EN 61207-6:2015
IEC 61207-6 Edition 2.0 2014-11 INTERNATIONAL STANDARD NORME INTERNATIONALE Expression of performance of gas analyzers –
Part 6: Photometric analyzers
Expression des performances des analyseurs de gaz –
Partie 6: Analyseurs photométriques
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE S ICS 19.080: 71.040.40 PRICE CODE CODE PRIX ISBN 978-2-8322-1936-2
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. SIST EN 61207-6:2015
– 2 – IEC 61207-6:2014 IEC 2014 CONTENTS FOREWORD . 3 INTRODUCTION . 5 1 Scope and object . 6 2 Normative references . 6 3 Terms and definitions . 7 4 Procedure for specification . 13 4.1 General . 13 4.2 Specification of essential ancillary units and services . 13 4.3 Additional terms related to the specification of performance . 13 5 Recommended standard values and range of influence quantities . 14 6 Procedures for compliance testing . 14 6.1 Verification of performance values . 14 6.2 Test equipment . 14 6.3 Simulation of duct width . 14 6.4 Testing procedures . 15 6.4.1 General . 15 6.4.2 Linearity uncertainty . 15 6.4.3 Interference uncertainty . 15 6.4.4 Delay time, rise and fall time . 16 Annex A (normative)
Techniques and systems of photometric analysis . 17 Annex B (informative)
Methods of preparation of water-vapor in test gases. 20 Bibliography . 22
Figure A.1 – Wavelength range for photometric measurements . 17 Figure A.2 – Analysis systems for gases . 17 Figure A.3 – Test apparatus to apply gases and water vapor to analysis systems . 18 Figure A.4 – Test apparatus to simulate duct conditions
for in-situ/across-duct analyzers . 19
SIST EN 61207-6:2015
IEC 61207-6:2014 IEC 2014 – 3 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
EXPRESSION OF PERFORMANCE OF GAS ANALYZERS –
Part 6: Photometric analyzers
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61207-6 has been prepared by sub-committee 65B: Measurement and control devices, of IEC technical committee 65: Industrial-process measurement, control and automation. This second edition cancels and replaces the first edition published in 1994. This edition constitutes a technical revision. The major changes with respect to the previous edition are as follows. – All references (normative and informative) have been updated, deleted or added to as appropriate. – All the terms and definitions relating to the document have been updated where appropriate. – New definitions have been added for generic photometric equipment and measurements. SIST EN 61207-6:2015
– 4 – IEC 61207-6:2014 IEC 2014 – All references to “errors” have been replaced by “uncertainties” and appropriate updated definitions applied. – Figures A.1, A.2 and A.4 have been updated. The text of this standard is based on the following documents: FDIS Report on voting 65B/947/FDIS 65B/956/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 61207 series, published under the general title Expression of performance of gas analyzers, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended.
SIST EN 61207-6:2015
IEC 61207-6:2014 IEC 2014 – 5 – INTRODUCTION
Photometric analyzers utilize detectors which respond to wavelengths in the ultraviolet, visible and infrared part of the electromagnetic spectrum within the wavelength range 0,1 µm to
50 µm (see Figure A.1). Within this range of wavelengths, many gases have absorption and/or emission bands. Analyzers designed to utilize these bands employ several techniques, including sensing of specific absorbed radiation by the sample gas or emitted radiation from the gas sample after artificial excitation. The volume of gas measured may be contained within a sample cell and this sample may or may not be conditioned, or (for in-situ analyzers) the concentration may be directly measured within the sample gas itself (see Figure A.2).
SIST EN 61207-6:2015
– 6 – IEC 61207-6:2014 IEC 2014 EXPRESSION OF PERFORMANCE OF GAS ANALYZERS –
Part 6: Photometric analyzers
1 Scope and object This part of IEC 61207 applies to all aspects of analyzers using photometric techniques for the measurement of concentration of one or more components in a mixture of gases or vapors. It should be used in conjunction with IEC 61207-1. For photometric analyzers utilizing tuneable semiconductor laser absorption spectroscopy (TSLAS) for gas measurements, IEC 61207-7 should also be referred to. This part of IEC 61207 applies to analyzers using non-dispersive and dispersive wavelength selection and using absorption, emission, wavelength derivative or scattering techniques. It applies to analyzers which receive either a conditioned or unconditioned sample of gas either under vacuum, at ambient pressure or pressurized. It applies to analyzers which measure gas concentrations directly within the sample gas. The object of this part is:
– to specify the terminology and definitions related to the functional performance of gas analyzers, utilizing a photometric analyzer, for the continuous measurement of gas or vapor concentration in a source gas;
– to unify methods used in making and verifying statements on the functional performance of such analyzers; – to specify what tests should be performed to determine the functional performance and how such tests should be carried out; – to provide basic documents to support the application of standards of quality assurance ISO 9001. 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. IEC 60079-29-1, Explosive atmospheres – Part 29-1: Gas detectors – Performance requirements of detectors for flammable gases
IEC 60079-29-4, Explosive atmospheres – Part 29-4: Gas detectors – Performance requirements of open path detectors for flammable gases IEC 60654 (all parts), Operating conditions for industrial-process measurement and control equipment IEC 61207-1, Expression of performance of gas analyzers – Part 1: General SIST EN 61207-6:2015
IEC 61207-6:2014 IEC 2014 – 7 – IEC 61207-7, Expression of performance of gas analyzers – Part 7: Tuneable semiconductor laser gas analyzers ISO 9001, Quality management systems – Requirements 3 Terms and definitions For the purposes of the present document, the following terms and definitions apply. NOTE The following definitions and examples of equipment and measuring techniques are for illustration and do not constitute a complete list of all possible measurement types. See Figure A.1 for the relationship between the different optical wavelength ranges. 3.1
light source device that emits light within the wavelength range 0,1 µm to 50 µm Note 1 to entry: A source may be, but is not limited to: a gas or solid state laser, semiconductor laser diode, light emitting diode, electric discharge source or incandescent filament. 3.2
light detector device that is sensitive to light and that may be used to detect light within the wavelength range 0,1 µm to 50 µm Note 1 to entry: A light detector may be, but is not limited to: a photomultiplier tube, semiconductor device (photovoltaic or photoconductive) such as a photodiode, avalanche photodiode or charge coupled device (CCD) and, additionally, in the infrared region: pyroelectric detector, bolometer or thermopile. 3.3
wavelength selection wavelength or range of wavelengths selected for use in particular measurement
Note 1 to entry: A suitable wavelength transmission range may be selected by using an appropriate means including a band-pass optical filter or dispersive element such as a diffraction grating.
Note 2 to entry: The wavelength from the light source may be tuned or modulated such as by using the current or temperature for a semiconductor laser diode, varying the temperature of an incandescent source or varying the input angle to a band-pass filter. 3.4
optical sample cell enclosed volume where the optical measurement of the sample gas takes place
Note 1 to entry: The optical measurement may take place by measuring the absorption or emission of the analyte after light of a suitable wavelength has been passed through an optical sample cell.
Note 2 to entry: The sample cell shall have some means of gas inlet and outlet, which may be via piping for flow or pressure driven systems or via diffusion through a mechanical filter.
Note 3 to entry: The cell may require a high integrity seal from the outside environment for extractive systems other than the gas inlet and outlet means.
Note 4 to entry: Cell windows of the appropriate optical transmission band are required for the light ingress and egress.
Note 5 to entry: Internal mechanical or optical features of the sample cell may be used to decrease stray light interference or to direct or concentrate the light where appropriate.
Note 6 to entry: The cell is designed to give an optical path length which is appropriate to the analyte and range required. SIST EN 61207-6:2015
– 8 – IEC 61207-6:2014 IEC 2014 3.5
multi-pass sample cell optical sample cell with increased effective absorption light path achieved by multiple reflections within the optical cavity of the sample cell Note 1 to entry: The effect of the multi-pass cell is to increase the sensitivity of the measurement for the same total cell length.compared to a single pass cell.
Note 2 to entry: Typical design models used include Herriott or White cells. 3.6
environmental monitoring gas analyzer
photometric gas analyzer used for environmental monitoring purposes 3.6.1
open path monitoring optical measurement where no containment for the sample gas is required
Note 1 to entry: This may be across a large space or an external measurement path.
Note 2 to entry: Typically, the light source and detector are separated by a distance and aligned to give a straight line absorption pathway.
Note 3 to entry: The net absorption will be the integrated effect across the whole of the absorption path length. 3.6.2
point monitoring monitoring giving localized gas concentration information Note 1 to entry: This gives monitoring information from a localized position rather than averaged data across an extended path length as per 3.6.1. 3.7
in-situ analyzer analyzer where the volume of gas sensed, that is gas within the measuring path for a photometric analyzer, is situated within the process source fluid Note 1 to entry: An in-situ analyzer may contain a fixed-length measuring cell within the duct and hence its calibration is not affected by the dimensions of the duct. 3.7.1
across duct or cross stack analyzer analyzer where the measuring path is formed by the entire width of a process duct or stack Note 1 to entry: The radiation source and detector can be mounted on opposite sides of the duct, or both can be mounted on the same side and a retroreflector employed. Where the retroreflector is within the duct, the analyzer is of the in-situ type. 3.7.2
across process line or pipe analyzer analyzer where the measuring path is formed by the entire width of a process pipe Note 1 to entry: The radiation source and detector can be mounted on opposite sides of the pipe, or both can be mounted on the same side and a retroreflector employed. Where the retroreflector is within the duct, the analyzer is of the in-situ type. 3.7.3
across firebox or other open process analyzer analyzer where the measuring path is formed by the entire width of a firebox or other open process path 3.7.4
inside process line or duct analyzer analyzer where the measuring path or point is inside the process duct itself SIST EN 61207-6:2015
IEC 61207-6:2014 IEC 2014 – 9 – 3.8
extractive analyzer analyzer which receives a continuous stream of gas withdrawn from a process by a sample handling system 3.8.1
close coupled extractive analyzer gas analyzer where the sensors are mounted at, or as close as possible to, the process take off point with a short extraction loop (typically <1 m) and with minimal sample handling, typically just particulate filtration 3.8.2
remote extractive analyzer gas analyzer which is situated remote from the process to be measured (typically >1 m)
Note 1 to entry: This may require further sample handling, including maintaining the sample at an elevated temperature to avoid condensation. 3.9
sample-handling system system which connects one or more process analyzers with the source fluid and the disposal points Note 1 to entry: The performance of this system is not dealt with in this part except for dilution sampling systems. 3.10
dilution sampling system system which samples process fluid and adds a diluent to the sample stream prior to measurement Note 1 to entry: This type of system generally applies calibration gas prior to the dilution point and hence the dilution system is treated as part of an in-situ analyzer for the purposes of this part of IEC 61207. 3.11
conditioned sample continuous stream of gas withdrawn from the source gas and filtered, cooled, and dried to within specified limits before application to a sampling analyzer 3.12
heated sample continuous stream of gas withdrawn from the source gas, which may or may not be filtered but is maintained at a temperature above its dew-point, including within the analyzer 3.13
opacity absorption of radiation, at the wavelengths used for measurement, by components of the sample gas, other than the component to be measured
Note 1 to entry: For example, this may be produced by dust or other contamination. 3.14
essential ancillary units units without which the analyzer will not operate, e.g. ancillary electronic units processing sensor signals to produce the reading, dilution sampling system, air purge or other optical cleaning system, automatic calibration system, temperature or pressure compensation system SIST EN 61207-6:2015
– 10 – IEC 61207-6:2014 IEC 2014 3.15
analyzers using light absorption analyzers which detect the amount of light absorbed by a gas of interest from a light source through a sample gas to a light detector at a particular wavelength or wavelength range in order to determine its concentration 3.15.1
infrared absorption analyzer electro-optical instrument consisting of a single source or multiple sources of infrared radiation and one or more infrared detectors separated from the source by a measuring path, wherein the specific spectral absorption of the component of interest is determined within the wavelength range 0,7 µm to 50 µm Note 1 to entry: For the purpose of this part of IEC 61207, the analyzer is adjusted by the manufacturer to select only the spectral band(s) at which the component to be determined has its characteristic absorption, and the measuring path dimensions are appropriate for the rated range of concentration and application of the analyzer. Note 2 to entry: Specific spectral sensitivity is obtained by a selective component such as a selective source, selective detector or selective filter, gas-filled cell or dispersive element, or any combination of these components. 3.15.2
ultraviolet (visible) absorption analyzer analyzer as defined in 3.15.1 but where the spectral absorption of the component determined occurs at wavelengths between 0,1 µm and 0,7 µm, hence the source(s), detector(s) and other optical components operate in the visible light or ultraviolet part of the electromagnetic spectrum Note 1 to entry: The visible part of the spectrum is included in this definition for ease of reference. 3.15.3
dual-beam analyzer analyzer whereby the radiation passage through the measured gas and a reference gas follows separate physical paths 3.15.4
single-beam analyzer analyzer whereby the radiation follows a single path through the sample gas, and measuring and reference signals are derived from wavelength selection (see 3.3 for example), or for a single-beam single-wavelength analyzer, no reference signal is generated 3.15.5
dual-wavelength filter-correlation analyzer analyzer where measuring and reference signals are derived by optical filter wavelength selection within and outside an absorption band respectively
Note 1 to entry: These two signals are processed to derive a concentration value. 3.15.6
gas filter correlation analyzer analyzer where measuring and reference signals are derived by utilizing a cell (gas filter) filled with the gas to be measured to absorb selectively radiation corresponding to the fine structure of the absorption line spectrum of that gas and another, otherwise identical cell, filled with a non-absorbing reference gas
Note 1 to entry: The two signals are processed to derive a concentration value. Note 2 to entry: The gas-filled filter component may be part of the detector. SIST EN 61207-6:2015
IEC 61207-6:2014 IEC 2014 – 11 – 3.15.7
direct absorption analyzer absorption measurements where the change in signal magnitude at the light detector due to optical absorption by the gas of interest is directly used as a means to determine the concentration of the gas of interest in a sample gas 3.15.8
wavelength derivative analyzer analyzer which measures gas-component concentrations using wavelength modulation of the radiation, and thereby uses the first derivative or second derivative of intensity versus wavelength to measure the shape of the absorption band 3.15.9
tuneable semiconductor laser absorption spectroscopy
TSLAS method of gas measurement using a tuneable semiconductor laser diode to determine the amount of light absorbed after transmission through a sample gas
Note 1 to entry: The light output wavelength from a laser diode may be tuned by using temperature and/or drive current of the laser diode. This allows the laser output wavelength to be scanned across an individual absorption band or bands of an absorbing gas species. The absorption information gained may be used to determine the gas concentration of the target species.
Note 2 to entry: In addition to note 1, a higher frequency modulation may be superimposed onto this lower frequency scan across the absorption band, in order to obtain enhanced speciation and/or measurement accuracy. 3.15.10
wavelength modulation spectroscopy
WMS technique using TSLAS (see 3.15.9) where the laser optical frequency is typically modulated in the 10 kHz to 1 000 kHz region, usually in addition to a much lower frequency scan over the gas absorption line of interest Note 1 to entry: The modulated laser beam is passed through the sample gas and the transmitted beam is detected using a fast photo-detector and the signal is then processed (demodulated) to obtain the gas absorption profile with high signal to noise ratio. 3.15.11
frequency modulation spectroscopy
FMS technique similar to WMS (see 3.15.10) however, in FMS the optical frequency of the laser is m
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