1、BRITISH STANDARD BS EN ISO 2556:2001 Incorporating Amendment No. 1 to BS 2782-8: Method 821A:1979 (renumbers the BS as BS EN ISO 2556:2001) Plastics Determination of the gas transmission rate of films and thin sheets under atmospheric pressure Manometric method The European Standard EN ISO 2556:2000
2、 has the status of a British Standard ICS 83.140.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS EN ISO 2556:2001 This British Standard, having been prepared under the direction of the Plastics Standards Committee, was published under the authority of the Executive Board
3、and c o m e s i n t o e f f e c t o n 31 August 1979 BSI 31 October 2001 The following BSI references relate to the work on this standard: Committee reference PLC/17 Draft for comment 78/55155 DC ISBN 0 580 10905 4 Committees responsible for this British Standard Amendments issued since publication
4、Amd. No. Date of issue Comments 13432 31 October 2001 Implementation of the European StandardBS EN ISO 2556:2001 BSI 31 October 2001 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and field of application 1 2 Reference 1 3 Definition 1 4 Principle 1 5 Apparatu
5、s and materials 1 6 Test specimens 3 7 Procedure 3 8 Expression of results 4 9 Test report 6 Figure 1 Example of apparatus with overflowing 5.4, 1)a) 7 Figure 2 Example of apparatus without overflowing 5.4,2) 8BS EN ISO 2556:2001 ii BSI 31 October 2001 National foreword This British Standard is the
6、official English language version of EN ISO 2556:2000. The UK participation in its preparation was entrusted to Technical Committee PRI/21, Testing of plastics, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enqu
7、iries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The Bri
8、tish Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A Briti
9、sh Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front
10、 cover, an inside front cover, pages i and ii, the EN ISO title page, the EN ISO foreword page, pages 1 to 8, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS
11、O 2556 September 2000 ICS 83.140 English version Plastics Determination of the gas transmission rate of films and thin sheets under atmospheric pressure Manometric method (ISO 2556:1974) Matires plastiques Dtermination du coefficient de transmission dun gaz par les feuilles et plaques minces, sous p
12、ression atmosphrique Mthode manomtrique (ISO 2556:1974) Kunststoffe Bestimmung der Gasdurchlssigkeit von Folien und dnnen Tafeln unter atmosphrischem Druck Druckmessgert-Verfahren (ISO 2556:1974) This European Standard was approved by CEN on 8 September 2000. CEN members are bound to comply with the
13、 CEN/CENELEC Internal Regulations which 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 Central Secretariat or
14、 to any CEN member. This European Standard 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 Central Secretariat has the same status as the official versi
15、ons. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europ
16、ene de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart, 36 B-1050 Brussels 2000 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 2556:2000 EEN ISO 2556:2000 BSI 31 October 2001 Foreword The text
17、 of the International Standard from Technical Committee ISO/TC 61, Plastics, of the International Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC 249, Plastics, the Secretariat of which is held by IBN. This European Standard shall be gi
18、ven the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2001, and conflicting national standards shall be withdrawn at the latest by March 2001. According to the CEN/CENELEC Internal Regulations, the national standards organizations
19、 of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Switzerland and the United Kingdom.EN ISO 2556:2000 BSI 31 October 2001 1
20、 1 Scope and field of application This International Standard specifies a method for the determination of the gas transmission rate of plastics films and thin sheets. The limits of the values which can be measured are from 1 to 20 000 cm 3 /m 2 .d.atm. The method can be used for measurements made ei
21、ther with air or with other test gases. 2 Reference ISO/R 291, Plastics Standard atmospheres for conditioning and testing. 3 Definition 3.1 gas transmission rate the volume of gas which, under steady conditions, crosses unit area of the sample in unit time under unit pressure difference and at const
22、ant temperature. This volume is expressed at standard temperature and pressure the rate depends on the thickness of the test specimen, and the reliability of the results depends on the evenness of the specimen thickness the rate is usually expressed in cubic centimetres (at 0 C under standard atmosp
23、heric pressure per square metre per 24 h under a pressure difference of 1 atm (cm 3 /m 2 .d.atm) NOTE 1 The SI unit of gas transmission rate is fm/Pa.s: 1 fm (femtometre) = 10 15m; 1 cm 3 /m 2 .d.atm = 0,114 3 fm/Pa.s and; 1 fm/Pa.s = 8,752 cm 3 /m 2 .d.atm. NOTE 2 The standard atmospheric pressure
24、corresponds to the pressure of a mercury column 760 mm high: either 1 013 mbar or 101,3 kPa. 4 Principle The plastic test specimen separates two chambers numbered 1 and 2. Chamber 1 contains the test gas at atmospheric pressure. Chamber 2, of known initial volume, has the air pumped out until the pr
25、essure is practically zero, then is hermetically sealed. The quantity of gas which passes through the specimen from chamber 1 to chamber 2 is determined as a function of time by measuring the increases of pressure occurring in chamber 2 by means of a manometer. The transmission rate is calculated fr
26、om the values obtained, excluding the initial period during which the rate of passage of gas increases with time. 5 Apparatus and materials The apparatus which comprises the parts described in 5.1, 5.2, 5.3 and 5.4, and of which suitable examples are shown in Figure 1 and Figure 2, must be placed in
27、 an enclosure with the temperature constant to within 2 C during the test. 5.1 Metal cell consisting of two detachable parts, as follows: 1) an upper part forming the cylindrical chamber 1 to contain the test gas, provided with tubes for the entry and exit of the gas employed; 2) a lower part formin
28、g a plane and polished “test plate” of diameter 100 to 120 mm and having at its centre either: a) a cavity of about 20 mm diameter containing a perforated disc and below this a small empty space so that the total depth of the cavity is 12 to 15 mm (see Figure 1). In this type of apparatus a filter p
29、a- per must be interposed between the specimen and the test plate. The diameter of this filter paper must be near, but not greater than, the internal diameter of the gasket; or, b) a cavity about 60 mm diameter and a few millimetres deep, filled with a sintered disc of glass or of bronze (see Figure
30、 2).EN ISO 2556:2000 2 BSI 31 October 2001 The filter paper indicated in a) or the sintered disc indicated in b) are to support the test specimen while at the same time allowing the passage of gas. In case b) the upper part of the sintered disc must be level with the test plate so that the specimen
31、rests flat over its whole surface. The closed space below the test specimen forms chamber 2, and is attached to a capillary tube (5.2) forming the manometer and to a vacuum pump (5.5). The two parts of the cell are clamped together by means of an effective clamping device, a circular gasket of rubbe
32、r being used to isolate the cell completely from the external atmosphere and to prevent the passage of gas from chamber 1 to chamber 2 other than through the test specimen. NOTE It is recommended that a check of the airtightness of the apparatus should be made by carrying out a blank test in accorda
33、nce with the procedure of clause 7 but with the test specimen replaced by metal foil. The level of the mercury in the capillary must remain practically unchanged during a period of the same order as that needed for the proposed measurements. 5.2 Calibrated capillary tube about 1,5 to 2 mm internal d
34、iameter and 200 to 400 mm in length, connected to the base of the metal cell. A scale graduated to 0,5 mm indicates the mercury level in the capillary tube. 5.3 U-tube about 5 mm diameter, connected to the bottom of the capillary tube as shown in Figure 1 and Figure 2. One arm of the tube is closed.
35、 The other arm is joined to a vacuum stopcock (which can be connected to a vacuum pump) and to a mercury reservoir (5.4) into which the mercury can be poured by overflowing. 5.4 Mercury reservoir fixed to the arm of the U-tube connected to the vacuum stopcock. This fixing can be done by method 1) or
36、 2) described below. 1) Fixing directly to the U-tube arm (see Figure 1). This type of apparatus can be arranged to function either with or without overflowing of mercury during the test. a) In the case of apparatus with overflowing, the U-tube is filled with mercury up to the overflowing level whic
37、h also corresponds to the scale zero (as shown in Figure 1). During the test the mercury level is maintained constant by overflowing. Nevertheless the regulation of the level is not altogether perfect since the overflowing occurs jerkily. It may therefore be preferable to use the apparatus in the ma
38、nner described in b). b) In the case of apparatus without overflowing, the U-tube is only filled to a point appreciably below the overflowing level, so that the whole test is carried out without overflowing. In this case the scale zero is below the overflowing level and in the calculation a correcti
39、on is essential (see 8.2). 2) The reservoir may be fixed to a greatly enlarged portion of this arm of the tube (about 20 mm diameter) and there is no overflowing during the test (see Figure 2). 5.5 Vacuum pump giving a pressure at the most equal to 13 Pa (0,13 mbar or 0,1 mmHg) in the lower chamber,
40、 and a gauge to measure this pressure with an accuracy of 6 Pa (0,06 bar or 0,05 mmHg) or better. 5.6 Mercury barometer. 5.7 Thermometer which can be read to 0,5 C. 5.8 Mercury. 5.9 Test gases and drying column if required.EN ISO 2556:2000 BSI 31 October 2001 3 6 Test specimens The specimens shall b
41、e representative of the batch of sheet or film for test and free from marks or visible defects (creases, thin spots, porosity, holes, etc.). They shall be in the form of discs with a diameter, depending on the apparatus used, large enough to overlap the joint between the two portions of the metal ce
42、ll. This diameter is usually about 80 mm. At least three specimens must be tested. Specimens of hygroscopic materials shall be conditioned in the selected atmosphere, preferably one of the atmospheres defined in ISO/R 291. The duration of conditioning depends on the material and shall be specified.
43、7 Procedure Carry out the test within the enclosure specified in clause 5 controlled at 23 2 C, or if required at one of the other temperatures given in ISO/R 291. 7.1 Introduce the mercury into the reservoir (5.4). The quantity shall be such that, after pouring out the mercury into the capillary tu
44、be and the two arms of the U-tube, the level of the mercury is at the zero graduation of the capillary (and a portion overflows back into the reservoir when an apparatus used with overflowing 5.4, 1)a) is employed). 7.2 If an apparatus according to 5.1, 2)a) is used, place a circle of filter paper o
45、f sufficient size on the test plate. 7.3 Smear a very thin film of vacuum grease in the region of the joint, taking care not to put it on the filter paper. 7.4 Mount the specimen, then the rubber gasket, and finally the upper part of the metal cell. 7.5 Clamp the two parts of the cell together so th
46、at the joint is perfectly airtight. 7.6 Join the gas entry tube through the drying column to the reservoir of compressed gas. Pass the gas slowly into chamber 1 throughout the test. NOTE By agreement, the drying column may be omitted and gas with a known percentage humidity employed. This point must
47、 then be included in the test report. 7.7 Connect the stopcock to the vacuum pump and operate the pump until the pressure in chamber 2 is less than 27 Pa (0,2 mmHg), checked with the gauge described in 5.5. 7.8 Close the stopcock, then tilt the apparatus to cause the mercury to run into the capillar
48、y and the arms of the U-tube. Fix the apparatus upright so that the capillary tube is vertical. Check that the mercury level in the capillary is at the zero of the scale. If not, adjust the quantity of mercury by tilting the apparatus. If the apparatus is used with overflowing of mercury 5.4, 1)a),
49、a part of the mercury must be returned to the reservoir. In all cases the mercury must be at the same level in the three tubes (zero level of the scale). 7.9 Note the value h of the mercury level in the capillary as a function of time t, remembering that this value h is measured from the mercury level at the start of the test. NOTE During the test, the difference between the mercury levels in the two arms of the U-tube must always be small. If the mercury level in the closed arm is observed to rise
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