1、December 2010 Translation by DIN-Sprachendienst.English price group 11No part of this translation 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).I
2、CS 83.100!$lI“1735938www.din.deDDIN EN ISO 7231Polymeric materials, cellular, flexible Determination of air flow value at constant pressure-drop(ISO 7231:2010)English translation of DIN EN ISO 7231:2010-12Weich-elastische Polymerschaumstoffe Bestimmung der Luftdurchlssigkeit bei konstantem Druck (IS
3、O 7231:2010)Englische bersetzung von DIN EN ISO 7231:2010-12Matriaux polymres alvolaires souples Dtermination de lindice dcoulement dair chute de pression constante(ISO 7231:2010)Traduction anglaise de DIN EN ISO 7231:2010-12SupersedesDIN EN ISO 7231:1998-01www.beuth.deDocument comprises pagesIn cas
4、e of doubt, the German-language original shall be considered authoritative.1611.10 DIN EN ISO 7231:2010-12 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products” in collaboration with Technical Committe
5、e CEN/TC 249 “Plastics” (Secretariat: NBN, Belgium). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Committee NA 062-04-37 AA Prfung weich-elastischer Schaumstoffe. Amendments This standard differs from
6、DIN EN ISO 7231:1998-01 as follows: a) a warning statement has been included; b) a new method (method B) particularly suitable for materials with a low permeability to air has been included; c) precision data for method B have been included; d) an example showing how a computer-controlled apparatus
7、could be used to carry out method B has been included. Previous editions DIN EN ISO 7231: 1998-01 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7231 July 2010 ICS 83.100 Supersedes EN ISO 7231:1997English Version Polymeric materials, cellular, flexible - Determination of air flow value at
8、 constant pressure-drop (ISO 7231:2010) Matriaux polymres alvolaires souples - Dtermination de lindice dcoulement dair chute de pression constante (ISO 7231:2010) Weich-elastische Polymerschaumstoffe - Bestimmung der Luftdurchlssigkeit bei konstantem Druck (ISO 7231:2010)This European Standard was a
9、pproved by CEN on 2 June 2010. CEN members are bound to comply with the 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
10、 standards may be obtained on application to the CEN Management Centre or 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 noti
11、fied to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxem
12、bourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All righ
13、ts of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7231:2010: EContents EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 2 PageForeword3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle4 5 Method A.5 6 Method B.8 Annex A
14、(informative) Automatic measurements in method B 12 Foreword This document (EN ISO 7231:2010) has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products” in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by NBN. This European Standar
15、d shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January 2011, and conflicting national standards shall be withdrawn at the latest by January 2011. Attention is drawn to the possibility that some of the elements of thi
16、s 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. This document supersedes EN ISO 7231:1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countrie
17、s are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia
18、, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of ISO 7231:2010 has been approved by CEN as a EN ISO 7231:2010 without any modification. EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 3 WARNING Persons using this International Standard should be familiar with normal l
19、aboratory practice. This standard 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 to ensure compliance with any national regulatory conditions. 1 Scope This Internat
20、ional Standard specifies two methods for determining the air flow value of flexible cellular polymeric materials: method A, for conventional types of flexible cellular polymeric material; method B, for all types of flexible cellular polymeric material, but especially for materials with a low permeab
21、ility to air. NOTE 1 Air flow values can be used to give an indication of the effects of formulation and production variables on the cellular structure. NOTE 2 In this International Standard, the expression “conventional type of flexible cellular polymeric material” means types which are unsuitable
22、for sealing purposes. 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 references, the latest edition of the referenced document (including any amendments) applies. ISO/
23、TR 9272, Rubber and rubber products Determination of precision for test method standards 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 air flow value volume flow rate required to maintain a constant pressure differential across a flexible f
24、oam test piece 4 Principle A specified constant air pressure differential is created across a standard flexible foam specimen. The rate of flow of air required to maintain this pressure differential is the air flow value. EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 4 5 Method A 5.1 Apparatus 5.1.1
25、General Diagrams of suitable apparatus are shown in Figure 1 (using an air pressure below atmospheric) and Figure 2 (using an air pressure above atmospheric). The essential parts are described in 5.1.2 to 5.1.5. 5.1.2 Flow-meters Low-pressure-drop flow-meters with an accuracy of up to 2 % are requir
26、ed for air flow measurements. The actual air flow shall be adjusted by a combination of valve restriction, as shown in Figures 1 and 2, and blower or vacuum pump speed, so that the required pressure difference across the specimen see 5.4 c) is maintained constant. Air flow-meters with at least 250 m
27、m scales are recommended. Flow-meters measuring in the range 0 dm3/s to 10 dm3/s will cover a wide variety of cellular polymeric materials. 5.1.3 Manometer A manometer graduated in the 0 Pa to 250 Pa range and with an accuracy of 2 % is required. Traps to prevent manometer fluid being drawn into the
28、 test chamber by accidental pressure changes shall be provided. A plunger in the fluid reservoir is used to set the zero point after levelling the manometer. The use of an inclined manometer with 2 Pa graduations is recommended. A level mounted on the manometer should be used to ensure that the prop
29、er degree of inclination from the horizontal is maintained. 5.1.4 Air supply or suction equipment The air supply or suction may be such that positive or negative pressure differences from atmospheric pressure are obtained across the test piece, using compressed air, an exhaust blower or a vacuum pum
30、p, etc. NOTE A particular apparatus can be constructed to use only positive or negative pressure. 5.1.5 Test piece mounting A chamber of nominal dimensions 140 mm diameter 150 mm depth (see Figure 1) or 75 mm diameter 1 000 mm length (see Figure 2), incorporating a test piece mounting and fittings f
31、or the manometer and exhaust, shall be provided. The test piece cavity shall be (50 0,05) mm (50 0,05) mm (25 0,05) mm. The test piece shall be supported by suitable means, for example by the use of vanes, wires or a perforated support. The support shall provide a minimum open proportion of 70 % of
32、the overall area, evenly distributed over its area (see Figures 1 and 2 for the positioning of the supports). Manometer and exhaust fittings shall be as shown in Figures 1 and 2. 5.1.6 Test chamber operated at below atmospheric pressure The apparatus, shown in Figure 1, shall be checked for leaks in
33、 the following manner: a) Seal the test piece mounting cavity with masking tape. b) With all the flow-meter valves closed, turn the air supply to approximately one-third of the maximum setting and observe any movement of the manometer. The manometer reading shall not exceed 1 Pa after 30 s. c) Open
34、the valve on the lowest-range flow-meter very slightly. The flow shall be essentially zero, as shown by a movement of less than 3 mm of the flow-meter float from its static position. EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 5 5.2 Test pieces The test pieces shall normally be in the form of a rig
35、ht parallelepiped of dimensions (51,0 0,3) mm (51,0 0,3) mm (25,0 0,3) mm. If test pieces of a different thickness are used, the thickness shall be stated in the test report. Any test pieces with length or breadth dimensions outside the required tolerance shall be discarded as they will lead to inac
36、curate air flow values. The test pieces shall be cut out without deformation of the original cell structure. Three test pieces shall be tested. NOTE Test pieces both with and without surface skin can be tested by this method, but the results will not be comparable. 5.3 Test conditions Testing shall
37、be carried out under the standard conditions of either (23 2) C and (50 5) % relative humidity or (27 2) C and (65 5) % relative humidity, unless otherwise specified. NOTE Since the flow-meter calibration is sensitive to temperature, the results obtained with these two sets of conditions will not ne
38、cessarily be comparable. 5.4 Procedure The method of measurement shall be as follows: a) Place the test piece in the test cavity with any skin on the side exposed to the lower pressure. Make sure that the test piece is free from undue strain and that a good air seal is obtained between the edges of
39、the test piece and the apparatus. b) Close the flow-meter valves and switch on the blower or vacuum pump. c) Open the high-range flow-meter slowly and adjust the air flow to obtain a pressure differential of (125 1) Pa on the manometer. d) If this reading is less than 10 % of full scale, close the v
40、alve of this flow-meter and open the medium-range flow-meter valve. Repeat this procedure until the correct flow-meter has been selected and the reading obtained. For greater accuracy, it is preferable to use two adjacent flow-meters, holding the higher-range one steady on an appropriate graduation
41、mark and making the adjustment on the lower-range one. In this case, the air flow value is obtained from the sum of the two flow-meter readings after maintaining the pressure differential for 10 s. e) Record the reading obtained as described in step d), in cubic decimetres per second, as the air flo
42、w value for the specimen. 5.5 Test report The test report shall include the following information: a) a reference to this International Standard; b) the method used (method A); c) all details necessary to identify the material tested; d) the individual test results and the mean air flow value; e) if
43、 test pieces of thickness different from that specified in 5.2 were used, the thickness of the test pieces; f) the orientation of the test pieces with respect to the direction of any anisotropy and the presence or absence of any skins; g) the test conditions used, i.e. temperature, relative humidity
44、, apparatus type and pressure direction; h) the date of the test. EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 6 Dimensions in millimetres Key 1 inclined oil manometer 2 two-way ball valve 3 test piece 4 test piece support vanes 5 vacuum chamber 6 low-range air flow-meter 7 medium-range air flow-met
45、er 8 high-range air flow-meter 9 power supply 10 voltage control 11 vacuum pump 12 exhaust Figure 1 Method A: Air flow apparatus (using air pressure below atmospheric) EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 7 Dimensions in millimetres Key 1 high-range air flow-meter 2 medium-range air flow-met
46、er 3 low-range air flow-meter 4 valves 5 horizontal steel rods to retain test piece in position 6 wing nut 7 test piece 8 gasket 9 inclined manometer 10 air supply Figure 2 Method A: Air flow apparatus (using air pressure above atmospheric) 6 Method B 6.1 Apparatus 6.1.1 General An example of the ai
47、r flow test apparatus is shown in Figure 3. A computer may be connected to the pressure-measurement system for automatic measurement instead of using manometers (see Annex A). The essential parts of the apparatus are as described in 6.1.2 to 6.1.5. 6.1.2 Air orifice A metal plate with an orifice of
48、a suitable size shall be mounted in the partition in the cylindrical test chamber. Generally, 10 such plates with different sizes of orifice are available, and one of them is chosen according to the air flow value of the test piece. EN ISO 7231:2010 (E) DIN EN ISO 7231:2010-12 8 6.1.3 Clamping ring
49、A metal ring shall be used to hold the test piece on top of the cylinder as shown in Figure 3. It shall have a hole in the centre to allow air to pass through the central uncovered area of the test piece. The diameter of the hole is normally 70 mm, although holes of other diameters may be used, depending on the particular test apparatus. 6.1.4 Manometer Both inclined and vertical manometers are required: they shall be graduated to an accuracy of 2 %. The inclined-manometer range shall be 0 Pa to 250
