1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 2782-2:2012Rubber, vulcanized orthermoplastic Determinationof permeability to gasesPart 2: Equal-pressure methodBS ISO 2782-2:2012 BRITISH STANDARDNational forewordThis Br
2、itish Standard is the UK implementation of ISO 2782-2:2012. Together with BS ISO 2782-1:2012, it supersedes BS ISO 2782:2006, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PRI/22, Physical testing of rubber.A list of organizations represented on this
3、 committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2012. Published by BSI Standards Limited 2012ISBN 978 0 580 69682 4 ICS
4、 83.060 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2012.Amendments issued since publicationDate T e x t a f f e c t e d ISO 2012Rubber, vulcanized
5、 or thermoplastic Determination of permeability to gases Part 2: Equal-pressure methodCaoutchouc vulcanis ou thermoplastique Dtermination de la permabilit aux gaz Partie 2: Mthode qui-pressionINTERNATIONAL STANDARDISO 2782-2First edition 2012-06-01Reference number ISO 2782-2:2012(E)BS ISO 2782-2:201
6、2ISO 2782-2:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permi
7、ssion in writing 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.orgPublished in SwitzerlandBS ISO 2782-2:2012ISO 2782-2:2012(E)
8、 ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope 12 Normative references . 13 Terms and definitions . 14 Principle . 15 Apparatus 26 Calibration . 37 Test gas 38 Carrier gas . 39 Test pieces 39.1 Shape and dimensions 39.2 Preparation 39.3 Number of test pieces 39.4 Meas
9、urement of thickness 39.5 Time interval between forming and testing 310 Conditioning . 311 Test conditions . 312 Gas transmission area . 413 Calibration curve . 414 Procedure 415 Calculation and expression of results . 515.1 Gas transmission rate 515.2 Gas permeability coefficient . 516 Test report
10、. 5Annex A (normative) Calibration schedule 7BS ISO 2782-2:2012ISO 2782-2:2012(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
11、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
12、 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. D
13、raft 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 doc
14、ument may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 2782-2 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.Together with Part 1, it cancels and replaces ISO 2
15、782:2006, which has been technically revised.ISO 2782 consists of the following parts, under the general title Rubber, vulcanized or thermoplastic Determination of permeability to gases: Part 1: Differential-pressure methods Part 2: Equal-pressure methodiv ISO 2012 All rights reservedBS ISO 2782-2:2
16、012ISO 2782-2:2012(E)IntroductionThe measurement of the permeability of rubber to gases is important in the evaluation of compounds for products such as inner tubes, tubeless-tyre liners, hoses, balloons and other gas-containing products, as well as seals and diaphragms. The measurement is also of t
17、heoretical importance in the study of the characteristics of gas diffusion and gas solubility in relation to polymer structure. ISO 2012 All rights reserved vBS ISO 2782-2:2012BS ISO 2782-2:2012Rubber, vulcanized or thermoplastic Determination of permeability to gases Part 2: Equal-pressure methodWA
18、RNING Persons using this part of ISO 2782 should be familiar with normal laboratory practice. This part of ISO 2782 does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and t
19、o ensure compliance with any national regulatory conditions.1 ScopeThis part of ISO 2782 specifies a method for the determination of the gas transmission rate and gas permeability coefficient of vulcanized or thermoplastic rubber under conditions in which the overall pressure on each side of the rub
20、ber test piece is the same, using gas chromatography to determine the quantity of gas that permeates through the rubber.The method applies to vulcanized and thermoplastic rubbers of hardness not less than 35 IRHD (international rubber hardness degrees) and to both single gases and mixtures of gases.
21、2 Normative referencesThe 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 2782-1:2012, Rubber, vul
22、canized or thermoplastic Determination of permeability to gases Part 1: Differential-pressure methodsISO 18899:2004, Rubber Guide to the calibration of test equipmentISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods3 Terms and definitionsFor th
23、e purposes of this document, the terms and definitions given in ISO 2782-1 apply.4 PrincipleA test cell, maintained at constant temperature, is divided by a test piece into a gas supply side and a gas transmission side (see Figure 1). The test gas is supplied to the gas supply side and a carrier gas
24、 is passed through the gas transmission side. The pressure on both sides of the cell is equal (atmospheric pressure) but, since the partial pressure of the test gas is higher on the gas supply side, it diffuses through the test piece into the gas transmission side. The quantity of test gas passing t
25、hrough the test piece is measured using a gas chromatograph.In this method, measurements are possible on test gases containing water vapour, and it is also possible to analyse mixtures of gases to determine the components.INTERNATIONAL STANDARD ISO 2782-2:2012(E) ISO 2012 All rights reserved 1BS ISO
26、 2782-2:2012ISO 2782-2:2012(E)5 ApparatusThe apparatus consists of the test cell, a gas chromatograph, test gas and carrier gas supply systems and associated tubing and valves. An example of a test apparatus is shown in Figure 1.5.1 Test cell, consisting of a gas supply side and a gas transmission s
27、ide, such that, when a test piece is mounted in it, the gas transmission area is clearly defined. The gas supply side has a test gas inlet port and an exhaust port and the gas transmission side is connected to the carrier gas supply and, through a sampling loop, to the gas chromatograph. The materia
28、l of the test cell shall be unreactive with regard to the test gas and shall not absorb the gas used. The surfaces of the two halves of the cell which make contact with the test piece shall be smooth and flat to prevent any leakage of gas. A seal such as an O-ring may be used between these areas and
29、 the test piece, in which case the gas transmission rate of the seal shall be considerably lower than that of the material being tested so that it does not affect the result of the test. The diameter of the gas transmission area shall be within the range 10 mm to 150 mm, depending on the gas transmi
30、ssion rate expected.The cell shall be equipped with a heating system capable of raising the temperature to 80 C. The temperature accuracy shall be 1 C for temperatures from 40 C to 80 C.NOTE Examples of a heating system are an electric heating jacket and an oven designed to hold the test cell and te
31、st gas supply.5.2 Gas chromatograph, having a detector such as a thermal conductivity detector (TCD) or a hydrogen flame ionization detector (FID). The detector and column shall be suitable for the test gas used and of the required sensitivity.5.3 Test gas controller, in accordance with 6.1.4 of ISO
32、 2782-1:2012.5.4 Two temperature sensors, the first fitted in the test cell for measuring the test temperature and the second fitted in the flow of carrier gas to measure the temperature of the carrier gas. The sensors shall be capable of reading to within 0,1 C or better.Key1 gas supply side 6 test
33、 gas supply 11 test gas controller2 gas transmission side 7 carrier gas supply 12 carrier gas controller3 test piece 8 three-way valve 13 sampling loop with thermometer4 sealing ring 9 gas chromatograph 14 gas transmission area5 temperature sensor 10 data-processing unit Figure 1 Example of gas perm
34、eability measuring apparatus (diagram at right shows an exploded view of the test cell)2 ISO 2012 All rights reservedBS ISO 2782-2:2012ISO 2782-2:2012(E)6 CalibrationThe test apparatus shall be calibrated in accordance with the schedule given in Annex A7 Test gasUse a single gas, such as nitrogen, o
35、xygen or hydrogen, or a mixture of gases, such as air, liquefied petroleum gas (in gaseous form) or coal gas. The purity of a single gas or the purity of each component in a gas mixture shall be 99,5 % by volume or higher, unless otherwise agreed between the interested parties, in which case a gas o
36、f lower purity may be used. The test gas shall not include any impurity that might affect the measurement.When using a gas mixture, the purity of each component shall be verified in advance with a suitable instrument, such as a gas chromatograph.When using a toxic and/or flammable gas, all necessary
37、 precautions should be taken in its use and in its recovery or disposal.8 Carrier gasSee 6.4 of ISO 2782-1:2012.9 Test pieces9.1 Shape and dimensionsSee 5.4.1 of ISO 2782-1:2012.9.2 PreparationSee 5.4.2 of ISO 2782-1:2012.9.3 Number of test piecesSee 5.4.3 of ISO 2782-1:2012.9.4 Measurement of thick
38、nessSee 5.4.4 of ISO 2782-1:2012.9.5 Time interval between forming and testingSee 5.4.5 of ISO 2782-1:2012.10 ConditioningSee 5.5 of ISO 2782-1:2012.11 Test conditionsSee 5.6 of ISO 2782-1:2012.For the test gas and carrier gas, the standard pressure is atmospheric pressure. ISO 2012 All rights reser
39、ved 3BS ISO 2782-2:2012ISO 2782-2:2012(E)12 Gas transmission areaSee 5.7 of ISO 2782-1:2012.13 Calibration curveInject a known quantity of the test gas into the gas chromatograph using a syringe or gas sampler. Determine the area of the peak in the chromatogram corresponding to the gas of interest.
40、Repeat the above measurements with at least three different levels of concentration and prepare a calibration curve from the data obtained.For a test gas mixture, a calibration curve for each component of the mixture shall be produced.14 Procedure14.1 Apply vacuum grease lightly and uniformly to the
41、 flat edges of the two halves of the test cell which will make contact with the test piece and mount the test piece in the lower part of the cell, without any wrinkling or sagging.14.2 Place a sealing ring (if used) on the test piece, followed by the upper part of the cell. Clamp the two halves of t
42、he cell together with uniform pressure so that the test piece is completely sealed in place.14.3 When making measurements at a temperature other than a standard laboratory temperature, bring the test cell to the test temperature.14.4 Purge both the gas supply side and the gas transmission side with
43、carrier gas by opening the three-way valve (8 in Figure 1) for a sufficient time, which will depend on the internal volume of the test cell and its connecting tubing. The flow rate is generally set at between 5 ml/min and 100 ml/min.14.5 Inspect the apparatus for leaks, then continue purging the app
44、aratus until the baseline, as measured by the recording device of the gas chromatograph, is stable. Record the carrier gas flow rate F and temperature T in the stable state.14.6 Switch the three-way valve to let the test gas flow into the gas supply side of the cell only.14.7 Adjust the test gas con
45、troller to give a constant flow rate, generally between 5 ml/min and 100 ml/min. The test gas diffusing through the test piece is carried by the carrier gas from the test cell into the sampling loop.14.8 At fixed intervals of time, turn the switch valve of the sampling loop to collect a sample of th
46、is gas and then pass it through the column of the gas chromatograph.14.9 Measure the area of the peak in the chromatogram corresponding to the test gas (or to each component of the test gas if the test gas is a mixture of gases). Determine the concentration of the test gas (or each component of the
47、test gas) in the carrier gas by means of the calibration curve(s).14.10 Repeat 14.8 and 14.9 until a constant value of the test gas concentration is obtained, and record the value w.4 ISO 2012 All rights reservedBS ISO 2782-2:2012ISO 2782-2:2012(E)15 Calculation and expression of results15.1 Gas tra
48、nsmission rateThe gas transmission rate is determined from Equation (1):GTRd= TAp TFw0 60 022710,(1)whereGTR is the gas transmission rate mol/(m2sPa);A is the gas transmission area (m2);pdis the partial pressure of the test gas on the gas supply side (Pa);T is the carrier gas temperature (K);T0is th
49、e standard-state temperature, in K (= 273,15);F is the carrier gas flow rate (m3/s);w is the test gas concentration (ppm);0,022 7 is the volume, in m3, of 1 mol of gas at a pressure of 0,1 MPa the volume of 1 mol of gas at 1 atm and 0 C is 0,022 4 m3(22,4 l), but it is 0,022 7 m3(22,7 l) at 0,1 MPa (1 bar).Express the gas transmission rate as the arithmetic mean of the results obtained for all the test pieces.15.2 Gas permeability coefficientThe gas permeability coefficient is determined from Equation (2)
