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1、BRITISH STANDARD BS ISO 6144:2003 Gas analysis Preparation of calibration gas mixtures Static volumetric method ICS 71.040.40 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 6144:2003 This British Standard was published under the au
2、thority of the Standards Committee and comes into effect on 25 March 2003 BSI 25 March 2003 ISBN 0 580 41469 8 National foreword This British Standard reproduces verbatim ISO 6144:2003 and implements it as the UK national standard. It supersedes BS 4559-3:1983 which is withdrawn. The UK participatio
3、n in its preparation was entrusted to Technical Committee PTI/15, Natural gas, 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 referre
4、d 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 provisio
5、ns 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
6、 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 iv, pages 1 to 29 and a back cover. The BSI
7、 copyright date 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 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 6144:2003(E) INTERNATIONAL
8、 STANDARD ISO 6144 Second edition 2003-02-01 Gas analysis Preparation of calibration gas mixtures Static volumetric method Analyse des gaz Prparation des mlanges de gaz pour talonnage Mthode volumtrique statique BS ISO 6144:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:22:00 GMT+00:
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14、fieldun, na, Mon Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iii Contents Page Forewordiv 1 Scope1 2 Normative references1 3 Terms and definitions.1 4 Principle .2 5 Apparatus.2 6 Procedure for preparing the calibration gas mixture4 7 Calculation of the volume fraction of the calibrat
15、ion component in the gas mixture7 8 Determination of the uncertainty in the concentration of the calibration component in the gas mixture 9 Annex A (informative) Example of an apparatus suitable for the preparation of calibration gas mixtures by the static volumetric method12 Annex B (informative) E
16、xample of determination of the volume of metering syringes 15 Annex C (informative) Example of the determination of the uncertainty in the concentration of a calibration gas mixture prepared by the static volumetric method.17 Annex D (informative) Example of the determination of the stability, as a
17、function of time, of prepared calibration gas mixtures 22 Bibliography29 BS ISO 6144:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of natio
18、nal 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. Internati
19、onal 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 rul
20、es 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
21、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 6144 was prepared by Technical Committee ISO/TC 1
22、58, Analysis of gases. This second edition cancels and replaces the first edition (ISO 6144:1981), which has been technically revised. BS ISO 6144:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS:4416 O3002(E) 1
23、 Gas analysis Preparation of calibration gas mixtures Static volumetric method 1 Scope This International Standard specifies a method for the preparation of calibration gas mixtures by a static volumetric method and provides a procedure for calculating the volumetric composition of the mixture. It c
24、an be used either with binary gas mixtures (containing one calibration component in a complementary gas, which is usually nitrogen or air1, 2) or with mixtures containing more than one component in the complementary gas. This International Standard also specifies how the expanded uncertainty in the
25、volume fraction of each calibration component in the mixture is determined by a rigorous evaluation of all the measurement uncertainties involved, including those associated with the apparatus used for the preparation of the gas mixture and those associated with the experimental procedure itself. NO
26、TE 1 This International Standard is generally applicable to the preparation of calibration gas mixtures containing calibration components in the concentration range 10 109 (10 ppb parts per billion) to 50 106 (50 ppm parts per million) by volume. However, gas mixtures may be prepared at larger or sm
27、aller volume fractions, provided that the components used in the static dilution process are selected appropriately. NOTE 2 A relative expanded uncertainty of not greater than 1 % at a level of confidence of 95 % may be achievable at these concentrations, provided that: the purities of the parent ga
28、ses have been determined by analysis and any significant impurities and the uncertainties in their measured concentrations have been taken into account; no significant adsorption effects or chemical reactions occur between the gaseous constituents and the internal surfaces of the apparatus, and ther
29、e are no reactions between any of the gaseous components, i.e. between the calibration component and complementary gas or between the calibration components themselves; all the relevant apparatus used in the preparation of a calibration gas mixture have been calibrated with assigned measurement unce
30、rtainties which are appropriate to calculating the final expanded uncertainty for the calibration gas mixture prepared. 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
31、references, the latest edition of the referenced document (including any amendments) applies. ISO 7504, Gas analysis Vocabulary 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 7504 apply. BS ISO 6144:2003 Licensed Copy: sheffieldun sheffieldun, na, M
32、on Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 4 Principle A calibration gas mixture consists of one of more calibration components in a complementary (diluent) gas, mixed in a suitable gas-mixing chamber. These calibration components are generally pure gases taken from cylinders, o
33、r from pure, volatile liquids that are allowed to evaporate into the gas-mixing chamber. The gas mixture is prepared using syringes to inject: either known volumes of gaseous calibration components (each at a pressure of about 1 105 Pa); or known masses or volumes of liquid calibration components; T
34、hese are injected into a volume of complementary gas contained in the mixing chamber (which is also at a pressure of about 1 105 Pa). Further complementary gas is then added to increase the overall pressure of the gas mixture to an accurately measured value above ambient atmospheric pressure. This f
35、inal (above- atmospheric) pressure is required so that the calibration gas mixture will subsequently flow out of the mixing chamber and can be used to calibrate a gas analyser, which is usually operated at ambient pressure. At each stage in the preparation procedure, the mixture is homogenized, usua
36、lly by means of a suitable stirring device, and then left to equilibrate to ambient atmospheric temperature. The volume fraction of each calibration component in the calibration gas mixture is determined by calculation of the ratio of the volume of the calibration component to the total volume of th
37、e mixture. 5 Apparatus 5.1 Gas-mixing chamber, consisting of the components specified in 5.1.1 to 5.1.8. NOTE An example of a suitable gas-mixing chamber is described in Annex A. 5.1.1 Vessel, comprising the gas-mixing chamber itself, of sufficient internal volume to deliver the amount of calibratio
38、n gas mixture required for any subsequent instrumental calibrations, manufactured of a suitable material that is inert to all the component gases, and designed both to be evacuable and to withstand the required above-atmospheric operating pressures. It shall also have vacuum/high-pressure flanges to
39、 allow access to the components that are mounted within the mixing chamber. NOTE 1 Vessels with internal volumes of 0,1 m3 to 0,5 m3, capable of operating up to pressures of about 2 105 Pa (2 bar) and of maintaining a vacuum of better than 0,1 102 Pa (0,1 mbar), have been found to be suitable (see A
40、nnex A). NOTE 2 Mixing chambers manufactured from borosilicate glass or stainless steel have been found to be suitable for the commonly used gaseous species (e.g. gas mixtures which contain SO2, NO, NO2, CO and C6H6 as the calibration components). However, care shall be taken in selecting the materi
41、als of the mixing chamber, and of the other components which come into contact with the gas mixtures, so that they do not affect the mixtures stability adversely particularly when more reactive gas mixtures are to be prepared. 5.1.2 Vacuum pump, capable of evacuating the mixing chamber and its assoc
42、iated components to a low pressure, and including a suitable vacuum shut-off valve. This low pressure shall be defined either so that any gaseous contamination resulting from the residual low pressure has no effect on the accuracy of the concentration of the gas mixture prepared, or so that a quanti
43、tative correction for the effect of this residual low pressure may be made to the concentration of the mixture. NOTE The residual gas pressure is generally due mainly to nitrogen from residual air. However, care must be taken to ensure that other gases that may react with the constituents of the gas
44、 mixture are not present at significant concentrations in this residual gas (e.g. traces of water vapour when acid gases are being used as calibration components, or traces of oxygen in the case when nitric oxide calibration mixtures are being prepared). 5.1.3 Gas line, used for the injection of the
45、 complementary gas, and including appropriate metering and shut-off valves. BS ISO 6144:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 04:22:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 3 5.1.4 Pressure, vacuum and temperature gauges, used to monitor these parameters inside the mixing
46、vessel. 5.1.5 Septum, enabling a gas or liquid of known volume or mass to be injected into the mixing chamber from a metering syringe (5.2). 5.1.6 Motor-driven gas-mixing device, e.g. a fan, enabling the gaseous components in the gas-mixing chamber to be homogenized, and designed to provide satisfac
47、tory mixing of all the gaseous components to a given degree of homogeneity within a specified time. Experimental tests shall be carried out to demonstrate that the mixing device is able to achieve the required homogeneity within the specified time. 5.1.7 Pressure relief valve, used to ensure that th
48、e maximum internal safe working pressure specified for the mixing vessel and its associated components is not exceeded. 5.1.8 Outlet-gas sampling line, enabling the gas mixture prepared to be used for calibration purposes, and having a device for equalizing the internal pressure of the gas mixture i
49、n the mixing chamber with atmospheric pressure so as to enable the gas mixture to be determined at ambient pressure for calibration purposes. 5.2 Calibrated metering syringe, which can be used to inject, by means of a piston, a known volume of gas or liquid through a needle. The syringe shall have gastight seals to ensure that no significant leakage of the gas or liquid takes place. NOTE 1 Glass syringes having polytetrafluoroethene (PTFE) bushings as