1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 7231:2010Polymeric materials, cellular,flexible Determination ofair flow value at constantpressure-drop (ISO 7231:2010)BS EN ISO 7231:2010 BRITISH STANDARDNational fore
2、wordThis British Standard is the UK implementation of EN ISO 7231:2010.It supersedes BS EN ISO 7231:1998 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/24, Testing of rigid and flexible cellular materials.A list of organizations represented on this
3、 committee 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. BSI 2010ISBN 978 0 580 57625 6ICS 83.100Compliance with a British Standard cannot confer immunity fromlegal
4、obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 August 2010.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 7231 July 2010 ICS 83.100 Supersedes EN ISO 7231:1997Engli
5、sh Version Polymeric materials, cellular, flexible - Determination of air flow value at constant pressure-drop (ISO 7231:2010) Matriaux polymres alvolaires souples - Dtermination de lindice dcoulement dair chute de pression constant (ISO 7231:2010) Weich-elastische Polymerschaumstoffe - Bestimmung d
6、er Luftdurchlssigkeit bei konstantem Druck (ISO 7231:2010)This European Standard was approved 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 an
7、y 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 Standard exists in three official versions (English, French, German). A version in any other language made
8、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 standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finlan
9、d, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOM
10、ITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 7231:2010: EBS EN ISO 7231:2010EN ISO 7231:2010 (E) 3 Foreword This document (EN ISO 7231:2010) has been
11、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 Standard shall be given the status of a national standard, either by publication of an identical text or by en
12、dorsement, 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 this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for id
13、entifying 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 countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Rep
14、ublic, 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 the United Kingdom. Endorsement notice The text of ISO 7231:2010 has b
15、een approved by CEN as a EN ISO 7231:2010 without any modification. BS EN ISO 7231:2010ISO 7231:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Principle1 5 Method A 2 6 Method B 5 Annex A (informative) Automatic measure
16、ments in method B9 BS EN ISO 7231:2010ISO 7231:2010(E) iv ISO 2010 All rights reservedForeword ISO (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 th
17、rough 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 collab
18、orates 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 Stan
19、dards. Draft 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
20、 this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 7231 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 4, Products (other than hoses). This second edition cancels and rep
21、laces the first edition (ISO 7231:1984), which has been technically revised. Major modifications in this revision are: a) the inclusion of a warning statement; b) the inclusion of a new method (method B) particularly suitable for materials with a low permeability to air; c) the inclusion of precisio
22、n data for method B; d) the inclusion of an example showing how a computer-controlled apparatus could be used to carry out method B. BS EN ISO 7231:2010INTERNATIONAL STANDARD ISO 7231:2010(E) ISO 2010 All rights reserved 1Polymeric materials, cellular, flexible Determination of air flow value at con
23、stant pressure-drop WARNING Persons using this International Standard should be familiar with normal laboratory 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 he
24、alth practices and to ensure compliance with any national regulatory conditions. 1 Scope This International 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,
25、for all types of flexible cellular polymeric material, but especially for materials with a low permeability 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 ex
26、pression “conventional type of flexible cellular polymeric material” means types which are unsuitable 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 unda
27、ted references, the latest edition of the referenced document (including any amendments) applies. ISO/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
28、 flow value volume flow rate required to maintain a constant pressure differential across a flexible foam 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
29、 is the air flow value. BS EN ISO 7231:2010ISO 7231:2010(E) 2 ISO 2010 All rights reserved5 Method A 5.1 Apparatus 5.1.1 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
30、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 required 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 th
31、e required pressure difference across the specimen see 5.4 c) is maintained constant. Air flow-meters with at least 250 mm 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 i
32、n the 0 Pa to 250 Pa range and with an accuracy of 2 % is required. Traps to prevent manometer fluid being drawn into the 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 incline
33、d manometer with 2 Pa graduations is recommended. A level mounted on the manometer should be used to ensure that the proper 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 differen
34、ces from atmospheric pressure are obtained across the test piece, using compressed air, an exhaust blower or a vacuum pump, 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
35、depth (see Figure 1) or 75 mm diameter 1 000 mm length (see Figure 2), incorporating a test piece mounting and fittings for 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 ex
36、ample by the use of vanes, wires or a perforated support. The support shall provide a minimum open proportion of 70 % of 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.
37、5.1.6 Test chamber operated at below atmospheric pressure The apparatus, shown in Figure 1, shall be checked for leaks in 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 ma
38、ximum setting and observe any movement of the manometer. The manometer reading shall not exceed 1 Pa after 30 s. c) Open 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 positi
39、on. BS EN ISO 7231:2010ISO 7231:2010(E) ISO 2010 All rights reserved 35.2 Test pieces The test pieces shall normally be in the form of a right 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 th
40、e test report. Any test pieces with length or breadth dimensions outside the required tolerance shall be discarded as they will lead to inaccurate 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
41、 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 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 spec
42、ified. NOTE Since the flow-meter calibration is sensitive to temperature, the results obtained with these two sets of conditions will not necessarily 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 expos
43、ed 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 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 th
44、e 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 valve 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 obtaine
45、d. For greater accuracy, it is preferable to use two adjacent flow-meters, holding the higher-range one steady on an appropriate graduation 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 maintainin
46、g the pressure differential for 10 s. e) Record the reading obtained as described in step d), in cubic decimetres per second, as the air flow 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
47、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 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 t
48、o the direction of any anisotropy and the presence or absence of any skins; g) the test conditions used, i.e. temperature, relative humidity, apparatus type and pressure direction; h) the date of the test. BS EN ISO 7231:2010ISO 7231:2010(E) 4 ISO 2010 All rights reservedDimensions in millimetres Ke
49、y 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-meter 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) BS EN ISO 7231:2010ISO 7231:2010(E) ISO 2010 All rights reserved 5Dimensions in millimetres Key 1 high-range air flow-meter 2 medium-range air flow-meter 3 low-range air
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