BS-ISO-6145-1-2003.pdf

BRITISH STANDARD BS ISO 6145-1:2003 Gas analysis Preparation of calibration gas mixtures using dynamic volumetric methods Part 1: Methods of calibration ICS 71.040.20 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 6145-1:2003 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 11 October 2004 © BSI 11 October 2004 ISBN 0 580 44539 9 National foreword This British Standard reproduces verbatim ISO 6145-1:2003 and implements it as the UK national standard. It supersedes BS 4559-5.1:1987 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PTI/15, Natural gas and gas analysis, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to vi, pages 1 to 32, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 6145-1:2003(E) © OSI 3002 INTERNATIONAL STANDARD ISO 6145-1 Second edition 2003-11-15 Gas analysis Preparation of calibration gas mixtures using dynamic volumetric methods Part 1: Methods of calibration Analyse des gaz Préparation des mélanges de gaz pour étalonnage à l'aide de méthodes volumétriques dynamiques Partie 1: Méthodes d'étalonnage BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) DPlcsid Fremia ihTs PDF file may ctnoian emdebt dedyfepcaes. 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In tlnu ehikletneve y ttah lborp aem leratit gno it is f,dnuo plsaee inform ttneC ehlar Secrteiraat ta the serddaig sleb nevwo. © ISO 3002 All irthgs erse.devr lnUeto sswrehise specified, on trap fo this lbupictaion maeb y cudorperro de tuilizi den yna form ro na ybm ynae,s lecetrinoc ro mecinahcal, inclidung tohpcoiypodna gn micrfoilm, wittuoh repmissii non writign from ietI rehSa Ot tsserdda eh ebolw or IS'Os memreb i ydobn the cnuotrfo y ttseuqer ehe.r ISO cirypothg fofice saCe tsopale 65 eneG 1121-HC 02 av leT. 4 + 10 947 22 1 11 xaF0 947 22 14 + 9 74 E-mail coirypthgiso.o gr We bwww.is.o gro Pulbisdehi n Switlrez dna ii © ISO 3002 Allr ihgtsser edevr BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) I ©SO 3002 All irhgts seredevr iii Contents Page Forewordiv Introduction v 1 Scope1 2 Normative references .1 3 Terms and definitions.1 4 Calibration methods .2 4.1 General.2 4.2 Description of primary or potentially primary measuring devices4 4.3 Measurements on the final mixture.12 5 Techniques for preparation of gas mixtures calibrated by the methods described in Clause 413 5.1 General.13 5.2 Volumetric pumps (see ISO 6145-23) 15 5.3 Continuous injection (see ISO 6145-44)15 5.4 Capillary (see ISO 6145-55).15 5.5 Critical orifices (see ISO 6145-66)16 5.6 Thermal mass flow controllers (see ISO 6145-77)16 5.7 Diffusion (see ISO 6145-88)16 5.8 Saturation (see ISO 6145-99)17 5.9 Permeation (see ISO 6145-1010).17 Annex A (normative) Volume measurement by weighing the water content.19 Annex B (informative) Description of secondary devices which need calibration against primary devices.23 Bibliography .32 BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) iv I ©SO 3002 All irhgts seredevr Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 6145-1 was prepared by Technical Committee ISO/TC 158, Analysis of gases. This second edition cancels and replaces the first edition (ISO 6145-1:1986), in which the estimated uncertainties in the calibration methods and techniques have now been combined in a square-root sum-of- squares manner to form the relative combined standard uncertainty. In comparison with the previous edition the periodic injection has been deleted (limited application). ISO 6145 consists of the following parts, under the general title Gas analysis Preparation of calibration gas mixtures using dynamic volumetric methods: Part 1: Methods of calibration Part 2: Volumetric pumps Part 4: Continuous injection methods Part 5: Capillary calibration devices Part 6: Critical orifices Part 7: Thermal mass-flow controllers Part 9: Saturation method Part 10: Permeation method Diffusion will be the subject of a future Part 8 to ISO 6145. Part 3 to ISO 6145, entitled Periodic injections into a flowing gas, has been withdrawn. BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) I ©SO 3002 All irhgts seredevr v Introduction This part of ISO 6145 is one of a series of standards which describes the various dynamic volumetric methods used for the preparation of calibration gas mixtures. In dynamic volumetric methods a gas, A, is introduced at volume or mass flow rate qA into a constant flow rate qB of a complementary gas B. Gas A can be either a pure calibration component, i, or a mixture of i in A. The volume fraction, i,M of i in the final calibration gas mixture is given in the following equation: A ,M,A AB ii q qq = + where i,A is the volume or mass fraction of component, i, in the pre-mixed gas A, and is already known from its method of preparation. It is assumed that in this equation, i,B, the concentration of component, i, in gas B, is zero. The introduction of gas A can be continuous (e.g. permeation tube) or pseudo-continuous (e.g. volumetric pump). A mixing chamber should be inserted in the system before the analyser and is particularly essential in the case of pseudo-continuous introduction. The flow rate of component A is measured either directly in terms of volume or mass, or indirectly by measuring the variation of a physical property. The dynamic volumetric preparation techniques produce a continuous flow rate of calibration gas mixtures into the analyser but do not generally allow the build-up of a reserve by storage under pressure. The main techniques used for the preparation of the mixtures are: a) volumetric pumps; b) continuous injection; c) capillary; d) critical orifices; e) thermal mass-flow controllers; f) diffusion; g) saturation; h) permeation; i) electrochemical generation. In all cases, and most particularly if very dilute mixtures are concerned, the materials used for the apparatus are chosen as a function of their resistance to corrosion and low absorption capacity (usually glass, PTFE or stainless steel). It should, however, be pointed out that the phenomena are less important for dynamic volumetric methods than for static methods. Numerous variants or combinations of the main techniques can be considered and mixtures of several constituents can also be prepared by successive operations. BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) vi I ©SO 3002 All irhgts seredevr Some of these techniques allow calculation of the final concentration of the gas mixture from basic physical information (e.g. mass rates of diffusion, flow through capillaries). However, since all techniques are dynamic and rely on stable flow rates, this part of ISO 6145 emphasizes calibration of the techniques by measurement of the individual flow rates or their ratios, or by determination of the composition of the final mixture. The uncertainty of the composition of the calibration gas mixture is best determined by comparison with a gas mixture traceable to international standards. Certain of the techniques which may be used to prepare a range of calibration gas mixtures may require several such traceable gas mixtures to verify their performance over that range. The dynamic volumetric technique used has a level of uncertainty associated with it. Information on the final mixture composition depends both on the calibration method and on the preparation technique. BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS-5416 O1:(3002E) I ©SO 3002 All irhgts seredevr 1 Gas analysis Preparation of calibration gas mixtures using dynamic volumetric methods Part 1: Methods of calibration 1 Scope This part of ISO 6145 specifies the calibration methods involved in the preparation of gas mixtures by dynamic volumetric techniques. It also gives a brief presentation of a non-exhaustive list of examples of dynamic volumetric techniques which are described in more detail in other parts of ISO 6145. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 6142, Gas analysis Preparation of calibration gas mixtures Gravimetric method ISO 6143, Gas analysis Comparison methods for determining and checking the composition of calibration gas mixtures ISO 7504, Gas analysis Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 7504 and the following apply. 3.1 uncertainty of measurement parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand NOTE 1 Values of the individual statistical uncertainties found in some methods and techniques in this part of ISO 6145 are combined with the values of systematic uncertainties that also occur in a square-root sum-of-squares manner to provide a relative combined uncertainty, or in some cases as a relative expanded uncertainty by application of the coverage factor “2”. NOTE 2 In keeping with Reference 1 of the Bibliography, the uncertainty of the composition of a mixture is expressed as a relative expanded uncertainty. BS ISO 61451:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:21:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI IS-5416 O1:(3002E) 2 I ©SO 3002 All irhgts seredevr 4 Calibration methods 4.1 General 4.1.1 The uncertainty in the composition i,M of a component i of a calibration mixture M depends at any time on a) the uncertainty of the calibration method, b) the frequency with which it is applied, c) the stability of the control devices involved in the dynamic preparation technique. To assess the uncertainty of the whole procedure, possible instantaneous variations and drift of the principle parameters of the technique during the calibration procedure shall be considered. According to the preparation technique for the gas mixtures used, calibration can be carried out by one of the following methods: measurement of flow rate (mass or volume); comparison method; tracer method; direct chemical analysis. Table 1 shows the applicability of each calibration method to the different preparation techniques. Table 1 Calibration methods applicable to the preparation techniques Calibration methods Preparation techniques Comparison with ISO 6143 a Flow rate measurement a Tracer a Direct analysis Volumetric pumps + + Continuous injection + + Capillary + + + Critical orifice + + + Thermal mass flow controllers + + + Diffusion + Saturation + Permeation + May be applicable; depends on nature of components a The pluses refer to the measurement of a volume flow. In principle, flow rate measurement can also be performed for continuous injection methods, diffusion methods and permeation methods. Here, mass flows are measured rather than volume flows. For diffusion and permeation tubes the mass flow may be measured continuously using a suspension balan