DIN EN ISO 6145-10-2008 Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 10 Permeation method (ISO 6145-10 2002) English version of DI.pdf

1、November 2008DEUTSCHE NORM English price group 12No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 71.040.40!$S.“1481156

2、www.din.deDDIN EN ISO 6145-10Gas analysis Preparation of calibration gas mixtures using dynamic volumetricmethods Part 10: Permeation method (ISO 6145-10:2002)English version of DIN EN ISO 6145-10:2008-11Gasanalyse Herstellung von Kalibriergasgemischen mit Hilfe von dynamisch-volumetrischenVerfahren

3、 Teil 10: Permeationsverfahren (ISO 6145-10:2002)Englische Fassung DIN EN ISO 6145-10:2008-11www.beuth.deDocument comprises 22 pagesDIN EN ISO 6145-10:2008-11 2 National foreword This standard has been prepared by Technical Committee ISO/TC 158 “Analysis of gases” (Secretariat: NEN, Netherlands) and

4、 has been taken over as EN ISO 6145-10:2008 by Technical Committee CEN/SS N21 “Gaseous fuels and combustible gas” (Secretariat: CMC). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NA 062-05-

5、73 AA Gasanalyse und Gas-beschaffenheit. 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 method Part 5: Capill

6、ary calibration devices Part 6: Critical orifices Part 7: Thermal mass-flow controllers Part 8: Diffusion method Part 9: Saturation method Part 10: Permeation method Part 11: Electrochemical generation The DIN Standards corresponding to the International Standards referred to in this document are as

7、 follows: ISO 6145-1 DIN EN ISO 6145-1 ISO 7504 DIN V 51897 In addition, it should be noted that the “Guide to the expression of uncertainty in measurement (GUM)” has been published as DIN V ENV 13005. National Annex NA (informative) Bibliography DIN V 51897, Gas analysis Definitions and explanation

8、s DIN V ENV 13005, Guide to the expression of uncertainty in measurement DIN EN ISO 6145-1, Gas analysis Preparation of calibration gas mixtures using dynamic volumetric methods Part 1: Methods of calibration EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6145-10 August 2008 ICS 71.040.40

9、English Version Gas analysis - Preparation of calibration gas mixtures using dynamic volumetric methods - Part 10: Permeation method (ISO 6145-10:2002) Analyse des gaz - Prparation des mlanges de gaz pour talonnage laide de mthodes volumtriques dynamiques - Partie 10: Mthode par permation (ISO 6145-

10、10:2002) Gasanalyse - Herstellung von Kalibriergasgemischen mit Hilfe von dynamisch-volumetrischen Verfahren - Teil 10: Permeationsverfahren (ISO 6145-10:2002) This European Standard was approved by CEN on 30 July 2008. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which

11、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 Management Centre or to any CEN member. This European Stan

12、dard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions. CEN members are the national st

13、andards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United K

14、ingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 6145-10:20

15、08: E2 DIN EN ISO 6145-10:2008-11 EN ISO 6145-10:2008 (E) Contents Page Foreword3 Introduction .4 1 Scope 5 2 Normative reference 5 3 Principle5 4 Reagents and materials 6 5 Apparatus .6 6 Procedure .9 6.1 Preliminary checks and operating conditions9 6.2 Determination of mass loss10 7 Expression of

16、results 11 7.1 Calculation11 7.2 Sources of uncertainty12 7.3 Estimation of uncertainties.14 7.4 Example calculation of uncertainties 17 Annex A (informative) Example of uncertainty calculation for a two-pan continuous weighing system 18 Bibliography20 Foreword 3 EN ISO 6145-10:2008 (E) DIN EN ISO 6

17、145-10:2008-11 The text of ISO 6145-10:2002 has been prepared by Technical Committee ISO/TC 158 “Analysis of gases” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 6145-10:2008 by Technical Committee CEN/SS N21 “Gaseous fuels and combustible gas” the sec

18、retariat of which is held by CMC. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by February 2009, and conflicting national standards shall be withdrawn at the latest by February 2009. Attention is

19、drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the foll

20、owing countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slo

21、venia, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 6145-10:2002 has been approved by CEN as a EN ISO 6145-10:2008 without any modification. Introduction This part of ISO 6145 is one of a series of standards dealing with various dynamic volumetric methods use

22、d for the preparation of calibration gas mixtures. 4 DIN EN ISO 6145-10:2008-11 EN ISO 6145-10:2008 (E) 1 Scope This part of ISO 6145 specifies a dynamic method using permeation membranes for the preparation of calibration gas mixtures containing component mole fractions ranging from 109and 106. A r

23、elative expanded uncertainty of 2,5 % of the component mole fraction can be achieved using this method. In the mole fraction range considered, it is difficult to maintain some gas mixtures, for example in cylinders, in a stable state. It is therefore desirable to prepare the calibration gas immediat

24、ely before use, and to transfer it by the shortest possible path to the place where it is to be used. This technique has been successfully applied in generating low content calibration gas mixtures of, for example, sulfur dioxide (SO2), nitrogen dioxide (NO2) and benzene (C6H6) in air. If the carrie

25、r gas flow is measured as a gas mass-flow, the preparation of calibration gas mixtures using permeation tubes is a dynamic-gravimetric method which gives contents in mole fractions. 2 Normative reference The following normative document contains provisions which, through reference in this text, cons

26、titute provisions of this part of ISO 6145. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 6145 are encouraged to investigate the possibility of applying the most recent edition of the

27、normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 6145-1, Gas analysis Preparation of calibration gas mixtures using dynamic volumetri

28、c methods Part 1: Methods of calibration 3 Principle The calibration component for example SO2, NO2, ammonia (NH3), benzene, toluene, xylene is permeated through an appropriate membrane into the flow of a carrier gas, i.e. the complementary gas of the mixture obtained. The calibration component, of

29、known purity, is contained in a tube, which is itself contained in a temperature-controlled vessel. This vessel is purged at a known and controlled flow rate by the carrier gas. The composition of the mixture is determined from the permeation rate of the calibration component as well as the flow rat

30、e of the high quality carrier gas, free from any trace of the calibration component and from any chemical interaction with the material of the permeation tube. The permeation rate of the calibration component through the membrane depends upon the component itself, the chemical nature and structure o

31、f the membrane, its area and thickness, the temperature, and the partial pressure gradient of the calibration component across the membrane. These factors can be kept constant by proper operation of the system. The permeation rate can be measured directly by mounting the tube on a microbalance and w

32、eighing the tube either continuously or periodically. 5 EN ISO 6145-10:2008 (E) DIN EN ISO 6145-10:2008-11 4 Reagents and materials 4.1 Permeating substances for calibration, of the highest possible purity so as to avoid any effect of impurities on the permeation rate; if this is not possible, the n

33、ature and quantities of the impurities shall be known and allowance made for their effect. 4.2 Carrier gas, of known purity, established by an appropriate analytical technique, for example, gas chromatography (GC) and/or Fourier transform infrared (FTIR) spectrometry. 5 Apparatus 5.1 Permeation appa

34、ratus, typically consisting of one of two modes (5.1.1 and 5.1.2) of application of the permeation method. The materials of the permeation apparatus shall be chosen so as to avoid any effect on the content of the calibration component by sorption (chemical or physical). The smaller the desired final

35、 content, the greater the effect of adsorption phenomena. If possible, use glass as the housing of the temperature-controlled permeation tube. Choose flexible and chemically inert tube materials and metals, especially having regard to the transfer of the gas between the permeation apparatus and the

36、analyser. Pay special attention to all junctions so as to keep them free from leaks. The flow range of the carrier gas is kept constant by a control system and is monitored by a flowmeter. The value of the flow rate can, for example, be controlled by means of a mass flow controller and determined us

37、ing a mass flowmeter. The existence of an outlet for surplus gas enables the analyser under calibration to take the gas flow rate necessary for its proper operation, the remainder of the flow of gas being vented to atmosphere. 5.1.1 Periodic-weighing-mode permeation apparatus, consisting of a permea

38、tion tube kept in a temperature-controlled enclosure, swept by carrier gas. The permeation tube is periodically removed from the enclosure to be weighed. Typical examples are given in Figures 1 and 2. 5.1.2 Continuous-weighing-mode permeation apparatus, consisting of a permeation tube kept in a temp

39、erature-controlled enclosure, swept by carrier gas. The permeation tube is suspended from a weighing device and weighed continuously. A typical example is given in Figure 3. 6 DIN EN ISO 6145-10:2008-11 EN ISO 6145-10:2008 (E) Key 1 Flowmeter 5 Thermometer 2 Carrier gas 6 Permeation tube 3 Drier 7 O

40、utlet for surplus gas 4 Filter 8 Analyser Figure 1 Example 1 of a periodic-weighing-mode permeation apparatus Key 1 Outlet for surplus gas 2 Sampling system 3 Mixing bulb 4 Flowmeter 2 5 Diluent gas 6 Thermometer 7 Permeation tube 8 Copper tubing 9 Water bath 10 Flowmeter 1 11 Carrier gas 12 Drier F

41、igure 2 Example 2 of a periodic-weighing-mode permeation apparatus 7 EN ISO 6145-10:2008 (E) DIN EN ISO 6145-10:2008-11 Permeation tube Mass flow controller Tare mass Key 1 High purity air/N2 2 Temperature controller 3 Water 4 Microbalance controller 5 Gas blender 6 RS232 link 7 PC (acquisition, ana

42、lysis and diagnostics) 8 16-bit ADC 9 Flow rate calibration facility 10 Gas analyser 11 Stable mixture requiring certification Figure 3 Continuous-weighing-mode permeation apparatus 8 DIN EN ISO 6145-10:2008-11 EN ISO 6145-10:2008 (E) 5.2 Permeation membrane, made from polymers and having sufficient

43、 chemical and mechanical resistance, e.g. suitable polytetrafluoroethylene (PTFE), polyethylene, polypropylene or a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP). Take into account variations of the material characteristics which occur with a change of temperature. 5.3 Permeation tu

44、bes, or containers, made of stainless steel or glass, fitted with a permeation membrane (5.2) and capable of holding the calibration component in the liquid phase and gaseous phase; the membrane through which the permeation takes place may be in contact with the liquid phase only, or with the gaseou

45、s phase only, or with both. See examples given in Figure 4. Before use, keep the permeation tube in an airtight container under an anhydrous atmosphere in a cold place (e.g. in a refrigerator at approximately 5 C) so as to maintain the diffusion rate as low as possible, hence to minimize loss of the

46、 calibration component and avoid any condensation on the tube. a) Cylindrical tube fitted with a membrane in contact with both phases b) Tube fitted with a membrane in contact with only the liquid phase c) Container fitted with a membrane in contact with only the gaseous phase Key 1 Membrane 2 Stain

47、less steel 3 Liquid level 4 Glass Figure 4 Examples of permeation tubes and container 6 Procedure 6.1 Preliminary checks and operating conditions 6.1.1 Permeation tube Before use, assess the purity of the product of the permeation tube by collecting a sample of the permeated gas for analysis by an a

48、ppropriate analytical technique e.g. GC or FTIR so as to quantify any likely major contaminants. This information may be provided by the suppliers of the tube and, if so, a certificate of analysis by an accredited body shall be provided. Periodically check the permeation rate of the tube at a known,

49、 fixed temperature by measuring the mass loss. This gives a good indication as to the purity of the permeated gas. If the permeation rate changes by more than 10 % at the known, fixed temperature, discard the permeation tube. When first using the permeation tube, allow the system to reach a state of equilibrium before carrying out the first weighing so as to ensure that the permeation rate is well stabilized at the constant value. The time needed to reach 9 EN ISO 6145-10:2008 (E) DIN EN ISO 6145-10:2008-11 equilibriu