CEN TR 16364-2012 Influence of materials on water intended for human consumption - Influence due to migration - Prediction of migration from organic materials using mathematical mo.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPD CEN/TR 16364:2012Influence of materials onwater intended for humanconsumption Influence dueto migration Predictionof migration from organicmaterials using mathematicalmodellin

2、gPD CEN/TR 16364:2012 PUBLISHED DOCUMENTNational forewordThis Published Document is the UK implementation of CEN/TR16364:2012.The UK participation in its preparation was entrusted to TechnicalCommittee EH/6, Effects of materials on water quality.A list of organizations represented on this committee

3、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 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 76777 7ICS 13.060.20Compli

4、ance with a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under the authority of theStandards Policy and Strategy Committee on 31 July 2012.Amendments issued since publicationDate Text affectedPD CEN/TR 16364:2012TECHNICAL REPORT RAPPORT TECHNIQU

5、E TECHNISCHER BERICHT CEN/TR 16364 June 2012 ICS 13.060.20 English Version Influence of materials on water intended for human consumption - Influence due to migration - Prediction of migration from organic materials using mathematical modelling Influence des matriaux sur leau destine la consommation

6、 humaine - Influence de la migration - Utilisation de modles mathmatiques pour prvoir la migration depuis des matriaux organiques Einfluss von Materialien auf Wasser fr den menschlichen Gebrauch - Einfluss infolge der Migration - Abschtzung der Migration aus organischen Materialien mittels mathemati

7、scher Modellierung This Technical Report was approved by CEN on 9 April 2012. It has been drawn up by the Technical Committee CEN/TC 164. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,

8、Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Mana

9、gement Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16364:2012: EPD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 2 Contents Page Foreword 4Introduction .51 Scope 72 Normative referenc

10、es 73 Terms and definitions .74 Principle 95 Apparatus .96 Assumptions that need to be valid 97 Required data inputs 107.1 General . 107.2 Diffusion coefficient of the substance (DP) 107.3 Partition coefficient of the substance (KP,W). . 107.4 Temperature of the system (T) 117.5 Geometry of the mate

11、rial . 117.6 Material thickness, (dP). 117.7 Initial concentration of the substance in the material (cP,0) . 117.8 Chemical identity of the substance and its relative molecular weight . 117.9 Specific gravity of the material (P) . 117.10 Simulation of contact of organic material with test water 118

12、Procedure 119 Expression of results . 1210 Report 12Annex A (informative) Principles of the modelling approach 14A.1 Migration modelling 14A.2 Initial and boundary conditions 14A.3 Solution of the diffusion equation 15A.4 Obtaining and using diffusion coefficients 15A.4.1 Diffusion coefficients from

13、 literature 15A.4.2 Diffusion coefficients from experiment 16A.4.3 Estimation of diffusion coefficients 16A.4.4 Upper-limit diffusion coefficient 17A.4.5 Validated AP, AP* and values . 18A.4.6 Diffusion coefficients for other materials 18A.4.7 Worst-case diffusion coefficients . 19A.5 Obtaining and

14、using partition coefficients 19A.5.1 General . 19A.5.2 Partition coefficients from literature and from experiment 19A.5.3 Partition coefficients from experiment . 20A.5.4 Estimation of partition coefficients. 20A.5.5 Worst-case partition coefficients 21Annex B (informative) Examples of the applicati

15、on of modelling to migration of substances from a material into drinking water 22B.1 Introduction . 22B.2 Contact conditions . 22B.3 Example calculations . 22PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 3 B.3.1 General . 22B.3.2 Example 1, cold water test with the material constant in accordance to 7 .

16、 23B.3.3 Example 2 Cold water test with “realistic” material constants (experimentally measured) . 24Annex C (informative) Validation of the numerical algorithm and software tools . 26C.1 General . 26C.2 Example A 27C.3 Example B 28Bibliography 32PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 4 Foreword

17、This document (CEN/TR 16364:2012) has been prepared by Technical Committee CEN/TC 164 “Water supply”, the secretariat of which is held by AFNOR. Attention is 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

18、responsible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 5 Introduction During the last two decades, several scientific investi

19、gations have demonstrated that migration from organic materials into liquid simulants is a physical process that can be modelled successfully. Mass transfer from an organic material into a liquid simulant is predictable because in many cases it follows Ficks law of diffusion, i.e. the diffusion proc

20、ess is the rate determining step. To predict migration from organic materials into contacting media a corresponding diffusion model was established. This Technical Report describes the application of predictive diffusion modelling to the estimation of the migration of a substance from a product inte

21、nded for contact with water intended for human consumption for convenience, and where appropriate, referred to as drinking water in this report. The application applies to organic materials, such as polymers, used to make such products. The purpose of the report is to stimulate the use of such techn

22、iques in member states such that sufficient experience is generated to enable the value of such modelling to be assessed in relation to complementing or substituting the conventional approach. Normally in member states the estimation of such migration is performed by standardised procedures based on

23、 laboratory testing and analysis, i.e. an experimental approach. Migration modelling is an alternative to this type of experimental testing. The experimental determination of the specific migration of substances into test water (simulated drinking water) often requires a considerable amount of time

24、and it can be costly. This conventional approach has worked well and, of course, it generates data on the actual concentration of a substance in test water. However, in some cases the analysis is difficult or even impossible due to problems caused, for example, by chemical degradation, volatilisatio

25、n of the substance. In addition, the substance may not be amenable to, or the target concentration of interest may be too low for, available analytical techniques Therefore, the application of a mathematical model could have considerable benefits for industry and regulators, as experience has shown

26、in the control of migration from plastic materials in contact with foodstuffs. Thus, the modelling approach is attractive because, in principle, it is quicker and more flexible than the conventional testing approach, in that different exposure conditions can be readily investigated - and it should b

27、e cheaper. Modelling of migration has been used for several years in the United States as an additional tool in support of regulatory decisions. Also, the European Union has introduced such diffusion modelling by means of EU Directive 2001/62/EC (the 6thamendment of Directive 90/128/EEC), consolidat

28、ed in Directive 2002/72/EC as a compliance and quality assurance tool for plastic materials intended to come in contact with foodstuff 3. The European project SMT-CT98-7513, Evaluation of Migration Models in Support of Directive 90/128/EEC, successfully demonstrated the practical value of such diffu

29、sion models. The main objectives of this project were to demonstrate: the validity of migration models for compliance purposes; that a relationship between the specific migration limit (SML) and the concentration of a substance in the finished product can be established. A report of this project has

30、 been finalised and the project results were published in a scientific journal 4. As indicated above, a major advantage of migration modelling is that it enables calculation of migration values independent of the limitations that affect the experimental/analytical approach. For example, at low cost

31、one can quickly investigate, for compliance or research purposes, a wide range of conditions of contact between material with test water. PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 6 The diffusion modelling approach described was originally developed for, and accepted by, the European Commission in t

32、he area of plastic materials in contact with foodstuffs. It has been successfully used to simulate the conventional experimental/analytical approach to compliance testing of plastics in contact with foodstuffs. In this latter approach different liquid food simulants, including aqueous simulants, are

33、 used. In principle, the approach is applicable to many organic materials. However, today it has been applied mainly to different types of polyethene, polypropene, polystyrene and polyvinyl chloride. Like the experimental approach, the mathematical approach has its limitations. An accurate predictio

34、n of the migration of a substance from an organic material to water requires detailed knowledge of the diffusion behaviour of the materials and substances under investigation. The level of information may well require extensive experimental studies more than the experimental, analytical approach wou

35、ld require. An important feature of the mathematical approach is the possibility of generalisation. Based on known average diffusion behaviour of polymers and substances, a maximum or upper-limit migration can be calculated. This so-called worst-case result may then be used for compliance purposes.

36、PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 7 1 Scope This Technical Report describes a procedure, based on a diffusion model, to be applied to the estimation of specific migration of substances into drinking water from organic materials intended to come into contact with drinking water. The modelling

37、 approach is readily applicable to certain organic materials, as explained in this report. In principle, the diffusion modelling approach is applicable to other organic materials but practical difficulties, in relation to obtaining data to feed into the diffusion model, may restrict or prevent its a

38、pplication. Accordingly, in addition to the diffusion model, scientific estimation procedures for the required data inputs need to be considered. The approach is normally applicable to organic substances that are soluble in the material matrix. Substances applied externally to a product made of an o

39、rganic material, e.g. antistatic agents, lubricants, etc. are excluded from the diffusion modelling approach, as are electrolytes, salts, oxides and metals. Only organic substances with well-defined molecular weight or mixtures with well-defined ranges of molecular weights are amenable to the diffus

40、ion modelling approach. The diffusion modelling approach is readily applicable to amenable organic materials in the form of a pipe or a sheet, where data such as material thickness is readily calculable. More complicated product shapes, such as fittings, require assumptions to be made. It may not be

41、 possible to model the effects of test waters that are chemically active, for example test waters to which chlorine has been added to simulate chlorinated drinking water. This is because substances that migrate from a material into water containing chlorine can be converted by chemical reaction into

42、 substances with different properties. 2 Normative references Not applicable. 3 Terms and definitions For the purpose of this document, the following terms and definitions apply. 3.1 diffusion model Ficks Second Law of diffusion that simulates the diffusion of substances from a material into drinkin

43、g water 3.2 experimental test technical operation that consists of the determination of one or more characteristics of a given product 3.3 experimental testing procedure set of instructions for determining by experiment the migration of a substance from a material into water 3.4 software tool set of

44、 instructions for a computer (e.g. a computer program) Note1 to entry: In this document it refers to instructions designed to model migration of substances from a material into water. PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 8 3.5 product manufactured item intended for contact with drinking water 3

45、.6 monolayer product this is or contains a material that consists of one layer 3.7 multilayer product this is or contains a material that consists of more than one layer 3.8 migration movement of a substance or substances from one compartment (a material) into a second compartment (water) 3.9 migrat

46、ion period period of time in which the migration is carried out under specified conditions 3.10 migration rate mass of a measured substance or substances migrating from the surface of a test piece into the test water in one day 3.11 substance chemical that is a constituent of a material used in cont

47、act with drinking water with the potential to migrate into drinking water 3.12 contact area surface area of a material in contact with a specific volume of water 3.13 volume to area ratio ratio of the volume of water in contact with a specific area of material 3.14 test water water used for migratio

48、n testing 3.15 diffusion equation partial differential equation known as Ficks Second Law that describes the variation of the concentration of a substance in a system (e.g. a polymer in contact with water) depending on time and location 3.16 diffusion coefficient factor of proportionality representi

49、ng the amount of substance diffusing across a unit area through a unit concentration gradient in unit time (e.g. from polymer to water) 3.17 molecular weight mass of one mole of molecules calculated using standard atomic weights, expressed as g/mol PD CEN/TR 16364:2012CEN/TR 16364:2012 (E) 9 3.18 partition coefficient ratio of the concentrations, at equilibrium, of a substance in the two phases of a mixture of two immiscible solvents Note1