1、BSI Standards PublicationBS ISO 19229:2015Gas analysis Purity analysisand the treatment of puritydataBS ISO 19229:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 19229:2015.The UK participation in its preparation was entrusted to TechnicalCommittee PTI/15,
2、 Natural Gas and Gas Analysis.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2
3、015. Published by BSI StandardsLimited 2015ISBN 978 0 580 85348 7ICS 71.040.40Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2015.Amendments issued since
4、publicationDate Text affectedBS ISO 19229:2015 ISO 2015Gas analysis Purity analysis and the treatment of purity dataAnalyse des gaz Analyse de puret et traitement des donnes de puretINTERNATIONAL STANDARDISO19229First edition2015-02-15Reference numberISO 19229:2015(E)BS ISO 19229:2015ISO 19229:2015(
5、E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an i
6、ntranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublis
7、hed in SwitzerlandBS ISO 19229:2015ISO 19229:2015(E)Contents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols 15 Principles . 25.1 General . 25.2 Assessment of critical and significant impurities . 25.2.1 Critical impurities . 25.2.2 Significant im
8、purities. 26 Analysis of impurities 36.1 General . 36.2 Purity analysis with results that are traceable 46.3 Indicative purity analysis . 56.4 No purity analysis . 66.5 Estimation of the amount-of-substance fractions of unmeasured (but expected) impurities 67 Use of purity data . 77.1 Calculation of
9、 the amount-of-substance fraction of the most abundant component 77.2 Calculation of the mass fraction of the most abundant component . 77.3 Calculation of the volume fraction of the most abundant component . 77.4 Other forms of purity data 8Bibliography 9 ISO 2015 All rights reserved iiiBS ISO 1922
10、9:2015ISO 19229:2015(E)ForewordISO (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
11、 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 Commissio
12、n (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should
13、 be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).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 ident
14、ifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenie
15、nce of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - S
16、upplementary informationThe committee responsible for this document is ISO/TC 158, Analysis of gases.iv ISO 2015 All rights reservedBS ISO 19229:2015ISO 19229:2015(E)IntroductionThe use of purity data in the calculation of the composition of calibration gas mixtures is an essential element in establ
17、ishing metrological traceability of the certified gas composition. Purity analysis is usually challenging, as normally, trace levels of various components need to be determined in a matrix for which limited or no measurement standards are readily available.In many practical situations, purity data i
18、n some form are available. For the preparation of calibration gas mixtures, it is important that this information is interpreted in a consistent fashion and taken into account in the calculation of the composition of the mixture. ISO 2015 All rights reserved vBS ISO 19229:2015BS ISO 19229:2015Gas an
19、alysis Purity analysis and the treatment of purity data1 ScopeThis International Standard sets requirements for the purity analysis of materials used in the preparation of calibration gas mixtures and the use of these data in calculating the composition of the mixture thus prepared.2 Normative refer
20、encesThe 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.ISO
21、 6143, Gas analysis Comparison methods for determining and checking the composition of calibration gas mixturesISO 7504, Gas analysis VocabularyISO 14912, Gas analysis Conversion of gas mixture composition dataISO/IEC Guide 98-3, Uncertainty of measurement Part 3: Guide to the expression of uncertai
22、nty in measurement (GUM:1995)3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 7504 apply.4 SymbolsIn this International Standard, the following symbols are used:i running index over the components in a mixturej index of the parent gask index of a speci
23、fic component in a mixtureLijlimit of detection of component i in parent gas ju standard uncertainty (of the quantity between brackets)wijmass fraction of component i in parent gas jxijamountofsubstance fraction of component i in parent gas jijvolume fraction of component i in parent gas jINTERNATIO
24、NAL STANDARD ISO 19229:2015(E) ISO 2015 All rights reserved 1BS ISO 19229:2015ISO 19229:2015(E)5 Principles5.1 GeneralThe determination of the impurities contained in each material (gas or liquid) used in the preparation has an impact on the uncertainty associated with the content of the component.A
25、ssess and list all of the impurities that might be present in the material. These can be identified by different means, including open literature, information provided with the material, previous experience of using the same or similar materials, and knowledge of the process used to produce the mate
26、rial.In order to decide the extent of purity analysis required, it is necessary to specify which of the potential impurities are critical and which are significant to the final composition of the mixture.5.2 Assessment of critical and significant impurities5.2.1 Critical impuritiesA critical impurit
27、y is an impurity that meets one or more of the following criteria: an impurity in the parent gas or liquid of a mixture that is also present as a minor component in the same mixture at low concentrations;EXAMPLE If preparing a low-concentration oxygen in nitrogen mixture, oxygen might also be presen
28、t as an impurity in the nitrogen. an impurity that has the potential to influence the result of an analytical verification of the mixture composition;EXAMPLE The presence of argon in nitrogen or oxygen will influence the analytical verification of the oxygen content when using gas chromatography wit
29、h a non-selective detector. an impurity in a parent gas or liquid of a multi-component mixture that is also present as a minor component in the same mixture;EXAMPLE For natural gas mixtures, i-pentane is often found as an impurity in n-pentane and neo-pentane, as well as being added as a minor compo
30、nent in its own right. an impurity that might be reactive with respect to any other component in the mixture.EXAMPLE If preparing a mixture of nitric oxide in nitrogen, any oxygen present as an impurity in the nitrogen might react with the nitric oxide to form nitrogen dioxide.5.2.2 Significant impu
31、ritiesA significant impurity is an impurity that is predicted to contribute more than 10 % to the target uncertainty of the content of any of the components in the calibration gas mixture. The application of this criterion requires knowledge of the preparation method used (e.g. gravimetric, volumetr
32、ic, static, or dynamic) and the uncertainties associated with the various steps involved.The above described steps are summarized as a flowchart in Figure 1. The use of the flowchart is explained in the following subclauses.2 ISO 2015 All rights reservedBS ISO 19229:2015ISO 19229:2015(E)list all cri
33、tical and other potential impuritiesasee 5.1carry out the steps below for each identig976ied impurity in turnnoyesis the impurity expected to be critical?see 5.2.1is the impurity expected to be signig976icant?see 5.2.2is the impurity expected to be signig976icant?see 5.2.2purity analysis with result
34、s that are traceable requiredsee 6.2indicative purity analysis requiredbsee 6.3yesno yesno purity analysis requiredcsee 6.4do the results indicate the presence of a signig976icant impurity?yesreport results of purity analysisnonoaIf an unpredicted or unknown impurity is identified during the course
35、of a purity analysis, return to the start of the flowchart.bIf preferred, a purity analysis with results that are traceable can be carried out instead of an indic-ative purity analysis.cIf preferred, a traceable or indicative purity analysis can be carried out.Figure 1 Purity analysis flowchart6 Ana
36、lysis of impurities6.1 GeneralThe extent of purity analysis required shall be determined by the outcome of the flowchart in Figure 1. Each of these levels is discussed in 6.2 to 6.4. ISO 2015 All rights reserved 3BS ISO 19229:2015ISO 19229:2015(E)The process shown in the flowchart in Figure 1 shall
37、be undertaken for each of the listed potential impurities. Purity analysis can be carried out by one or more appropriate analytical techniques. In some instances, more than one technique might be needed.EXAMPLE When determining the purity of methane, hydrocarbon impurities can most accurately be det
38、ermined by gas chromatography with flame ionization detection (GC-FID), while other impurities can be determined by GC with thermal conductivity detection (GC-TCD) or discharge ionization detection (GC-DID).For some materials (e.g. liquids and corrosive gases), it might not be practicable to analyse
39、 the material in its pure state. In these cases, an alternative approach can be taken such as the preparation of a gravimetric mixture with a lower amountofsubstance fraction for purity analysis (using a carefully chosen matrix gas of known high purity). This approach has, however, a detrimental eff
40、ect on the achievable limits of detection and that care should be taken to account for the purity of the matrix gas when calculating the purity of the component of interest.When using liquids or liquefied gases in gas mixture preparation, this phase shall be subjected to a purity analysis rather tha
41、n the vapour phase. If the vapour phase is used, this phase shall be analysed. As the compositions of the vapour and liquid phase differ, these compositions might change during use of the liquid/vapour. Appropriate measures shall be taken to ensure that the purity data remain valid within their stat
42、ed uncertainties.When carrying out a purity analysis, care should be taken to check for any unexpected impurities (i.e. any observed impurities that were not identified as a potential impurity when following the assessment procedure in 5.2). For example, when using gas chromatography, unexpected imp
43、urities can be observed as unexpected peaks in the chromatogram. If one or more unexpected impurities are observed, each should be assessed as to whether it is critical and/or significant, and the appropriate impurity analysis then carried out, as determined by the flowchart in Figure 1.6.2 Purity a
44、nalysis with results that are traceableTo carry out a purity analysis with results that are traceable, calibrate the analyser(s) using reference gas mixtures with defined uncertainties and quantify the impurity by direct comparison with these reference mixtures by use of methods described in, e.g. I
45、SO 6143.If metrologically traceable purity data from another source (e.g. on a certificate of analysis) are available, these data can be used for this purpose. The metrological traceability of the data shall be assessed, if not explicitly stated on the certificate/in the report provided. Such assess
46、ment shall include, but is not limited to, checking whether appropriate certified reference materials or other measurement standards have been used and a rigorous uncertainty evaluation of all steps leading to the measurement result has been performed.NOTE 1 A reference gas mixture is a mixture of a
47、ppropriate metrological quality that has composition data that are traceable to a national or international measurement standard through an unbroken chain of comparisons with stated uncertainties. An example is a gas mixture certified by a calibration laboratory, fulfilling the conditions stipulated
48、 in ISO/IEC 17025.NOTE 2 Where traceable gaseous measurement standards are not available, certified reference materials can be available in liquid form with certified purity.NOTE 3 Where appropriate measurement standards or certified reference materials are not available, it can be necessary to rede
49、sign the proposed preparation in a way that traceable purity analysis is not required, by using for example materials with better purity.NOTE 4 Where traceable measurement standards or certified reference materials are not available, it is sometimes possible to estimate the purity of starting materials by use of a kind of standard addition method. Prepare a series of standards containing the pure material at different concentrations and extrapolate the analysed values back to zero.4 ISO 2015 All rights rese
