1、BRITISH STANDARD BS EN 61207-2:1994 IEC 1207-2: 1994 Expression of performance of gas analyzers Part 2: Oxygen in gas (utilizing high-temperature electrochemical sensors) The European Standard EN 61207-2:1994 has the status of a British Standard UDC 621.317.79:543.27:543.25BSEN 61207-2:1994 This Bri
2、tish Standard, having been prepared under the directionof the Electrotechnical Sector Board, was published underthe authority of the Standards Board and comes intoeffect on 15November 1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PCL/- Draft f
3、or comment 85/21733 DC ISBN 0 580 23514 9 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises the national committees of the following countries: Austria Italy Belgium Luxembourg Denma
4、rk Netherlands Finland Norway France Portugal Germany Spain Greece Sweden Iceland Switzerland Ireland United Kingdom Amendments issued since publication Amd. No. Date CommentsBSEN 61207-2:1994 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Te
5、xt of EN 61207-2 3 National annex NA (informative) Committees responsible Inside back cover National annex NB (informative) Cross-references Inside back coverBSEN 61207-2:1994 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Electrotechnical Sector
6、Board and is the English language version of EN 61207-2:1994 Expression of performance of gas analyzers. Part 2: Oxygen in gas (utilizing high-temperature electrotechnical sensors), published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC 1207-2:19
7、94 including Corrigendum, May 1994, published by the International Electrotechnical Commission (IEC). IEC 1207-2 constitutes Part 2 of the IEC 1207 series of publications under the general title: Expression of performance of gas analyzers. Other Parts are as follows: Part 1: General; Part 2: Oxygen
8、in gas (utilizing high-temperature electrotechnical sensors); Part 6: Photometric analyzers; Part 7: Infra-red analyzers. Parts 3, 4 and 5 are under consideration. The following print types are used in this standard: requirements proper: in roman type; notes: in smaller roman type. A British Standar
9、d does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an
10、 inside front cover, pages i and ii, theEN title page, pages2 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EU
11、ROPENNE EUROPISCHE NORM EN 61207-2 June 1994 UDC 621.317.79:543.27:543.25 Descriptors: Gaseous mixtures, oxygen in gaseous mixtures, gas analyzers, performance of gas analyzers, high temperature electrochemical sensors English version Expression of performance of gas analyzers Part 2: Oxygen in gas
12、(utilizing high-temperature electrochemical sensors) (IEC 1207-2:1994 + corrigendum 1994) Expression des qualits de fonctionnement des analyseurs de gaz Partie 2: Oxygne contenu dans le gaz (utilisant des capteurs lectrochimiques haute temprature) (CEI 1207-2:1994) Angabe zum Betriebsverhalten von G
13、asanalysatoren Teil 2: Sauerstoff in Gas (unter Verwendung von elektrochemischen Hochtemperatur-Sensoren) (IEC 1207-2:1994) This European Standard was approved by CENELEC on 1994-05-15. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for g
14、iving 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 Central Secretariat or to any CENELEC member. This European Standard exists in three officia
15、l 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 Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committ
16、ees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europ
17、isches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1994 Copyright reserved to CENELEC members Ref. No. EN 61207-2:1994 EEN 61207-2:1994 2 BSI 11-1999 Foreword The text of document 65D(CO)3, as prepared by Subcommittee 65D: Analyzing equipment, of IEC
18、 Technical Committee 65: Industrial-process measurement and control, was submitted to the IEC-CENELEC parallel vote in October 1993. The reference document was approved by CENELEC as EN 61207-2 on 15 May 1994. The following dates were fixed: For products which have complied with the relevant nationa
19、l standard before 1995-05-15, as shown by the manufacturer or by a certification body, this previous standard may continue to apply for production until 2000-05-15. Annexes designated “normative” are part of the body of the standard. Annexes designated “informative” are given only for information. I
20、n this standard, Annex ZA is normative. Contents Page Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Procedures for specification 5 4.1 Specification of essential units and ancillary services 5 4.2 Additional terms related to the specification ofperformance 5 4.3 Impo
21、rtant terms related to the specification ofperformance 5 5 Procedures for compliance testing 6 5.1 General 6 5.2 Testing procedures 6 5.3 Output fluctuation 6 5.4 Delay time, rise time and fall time 6 Annex ZA (normative) Other international publications quoted in this standard with thereferences of
22、 the relevant European publications 10 Figure 1 General test arrangement, in situ analyser 8 Figure 2 General test arrangement, extractiveanalyzer 9 latest date of publication ofan identical national standard (dop) 1995-05-15 latest date of withdrawal ofconflicting national standards (dow) 1995-05-1
23、5EN 61207-2:1994 BSI 11-1999 3 Introduction This part of IEC 1207 includes the terminology, definitions, statements and tests that are specific to oxygen analyzers, which utilise high-temperature electrochemical sensors. Oxygen analyzers employing high-temperature electrochemical sensors operating a
24、t temperatures usually in excess of 600 C, have a wide range of applications for the measurement of oxygen in gas samples. Such samples are typically the result of a combustion process. Two main types of analyzer exist, the in situ analyzer, where the sensor is positioned within the process duct wor
25、k, and the “extractive” analyzer, where the sample is drawn from the duct via a simple sample system and presented to the sensor. An analyzer will typically comprise a sensor head, mounted on the process duct, and a control unit remotely mounted, with interconnecting cable. 1 Scope This part of IEC
26、1207 applies to all aspects of analyzers using high-temperature electrochemical sensors for the measurement of oxygen in gas. It should be used in conjunction with IEC 1207-1. It applies to in-situ and extractive analyzers and to analyzers installed indoors and outdoors. The object of this part is:
27、to specify the terminology and definitions related to the functional performance of gas analyzers, utilizing a high-temperature electrochemical sensor, for the continuous measurement of oxygen concentration in a sample of gas; to unify methods used in making and verifying statements on the functiona
28、l 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 ISO9001, ISO 9002 and ISO 9003. 2 Normative references
29、The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 1207. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of
30、IEC 1207 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 654, Operating conditions for industrial-process measurement and control e
31、quipment. IEC 1207-1:1994, Expression of performance of gas analyzers Part 1: General. 3 Definitions 3.1 High-temperature electrochemical sensor The high-temperature electrochemical sensor can be constructed in two basic forms: a) Galvanic concentration cell. b) Ion pump cell. 3.1.1 galvanic concent
32、ration cell most commercially available analyzers employ the galvanic concentration cell consisting of two gas chambers, separated by an oxygen ion conducting solid electrolyte, and provided with a porous electrode on each side NOTE 1Platinum is frequently used for the electrodes, and the ceramic el
33、ectrolyte is usually zirconium oxide, fully or partially stabilized with yttrium oxide, calcium oxide or thorium oxide, which when heated above 600 C, allows the charge transfer mechanism to be predominantly oxygen ion conduction. NOTE 2When the sensor is brought to a temperature at which the solid
34、electrolyte conducts oxygen ions and the e.m.f. between the two electrodes is measured, the output will be related to the logarithm of the ratio of the partial pressures of oxygen at each of the electrodes in accordance with the Nernst equation: (1) (2) (3) where P 1 is the partial pressure of oxyge
35、n in the reference gas; P 2 is the partial pressure of oxygen in the sample gas; E is the electromotive force output from the cell in V; R is the gas constant (8,3144 J K 1mol 1 ); T is the absolute temperature (K); F is the Faraday constant (96,484 56 10 3C mol 1 ); k is the Nernstian coefficient (
36、slope factor).EN 61207-2:1994 4 BSI 11-1999 Thus, provided the oxygen partial pressure is known at one electrode (P 1 ), then the potential difference between the two electrodes will enable the unknown oxygen pressure to be determined at the other electrode (P 2 ). The Nernstian response of the high
37、-temperature electrochemical ceramic sensor holds over a very wide range of oxygen partial pressures differences, and the sensor output increases logarithmically with linear reduction of the oxygen partial pressure at a given temperature. The sensor output is directly proportional to temperature, an
38、d hence for quantitative analysis, the temperature of the cell should be closely controlled or measured, and the necessary corrections applied in equation (1). NOTE 3Zero offset Theoretically the output e.m.f. of the sensor, when the partial pressures of the sample gas and reference gas are equal, i
39、s zero volts. In some sensors a zero offset is measured and is considered largely due to thermoelectric effects, and thermal gradients across the electrodes. This offset can be considered theoretically as an extra constant (asymmetry potential). Non-ideal oxygen ion conduction can also be compensate
40、d for by introducing modifications to the slope factor k. In practice, manufacturers whose sensors exhibit zero offset may supply practical average values of U to help in calibration. Modern equipment will automatically compensate the asymmetry potential during air point calibration (i.e. air in bot
41、h chambers). 3.1.2 ion pump cell If a direct current is made to flow between the electrodes of a cell, with air in one chamber and an inert gas in the other chamber, the current flow will cause a pumping of oxygen molecules from one side to the other. The action obeys Faradays laws and the quantity
42、of oxygen pumped by diffusion into the inert gas is given by: This is used generally in two basic configurations. 3.1.2.1 limiting current a diffusion pinhole limits the rate of arrival of oxygen molecules at the measuring electrode, and a constant voltage across the electrodes ensures that all the
43、oxygen arriving at the measuring electrode is pumped to the other side. The current generated is quantitatively related to the number of oxygen molecules transferred 3.1.2.2 fixed volume this configuration consists of two sets of electrodes arranged across a small fixed volume. The first set compris
44、es a concentration cell, the second set the ion pump. The volume is initially swept of oxygen molecules to a predetermined low level. Pump action is then initiated until the concentration cell reading shows that the oxygen concentration in the volume and that outside at the sample side, are the same
45、. The current and time required to achieve this are related to the oxygen concentration of the sample gas 3.2 reference gas all analyzers using the high-temperature electrochemical concentration cell require a reference sample of known and constant composition usually air is employed NOTEThe sensor
46、output is a function of the partial pressure of oxygen in the sample, provided the reference has a constant partial pressure of oxygen. 3.3 in situ analyzer the in situ analyzer has the high-temperature electrochemical sensor situated in the sample; however the sensor may require a filter to remove
47、particulates one version of the in situ analyzer controls the temperature of the sensor in the range 600 C to800 C. In this case the sample temperature cannot exceed the control temperature. The second version relies on the temperature of the sample to attain the operating temperature. It is then ne
48、cessary to measure the sensor temperature to enable the oxygen value to be calculated 3.4 extractive analyzer in the “extractive” analyzer the sensor head is installed outside the gas stream to be measured, and the sample is drawn through a sample probe and presented to the sensor which is maintaine
49、d at a controlled temperature to ensure ionic conduction (typically in the range 600 C to 800 C) the extractive analyzer may require a filter to remove particulates, and a driving force (often an aspirator) to move the sample. The pipework involved should be minimized and maintained above the dew-point of any condensible species to prevent formation of any condensation (4) (5) where U T is the asymmetry potential (mV). (6) where Q is the quantity of oxygen pumped in mol s 1 ; I is the current (A); F is the Faraday co
