4638 International Standard (ISo INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONMEKAYHAPOAHAR OPTAHW3ALMA NO CTAHAAPTW3AUMW+ORGANISATION INTERNATIONALE DE NORMALISATION Polymeric materials, cellular flexible -- Determination of air flow permeability Materiauxpolymeres alveolaires souples-Determinationdela permeabilitea /'air First edition - 1984-05-15 $0 4638-1984 (E) UDC 678.4-405.8 : 620.193.29 Ref.No.ISO4638-1984(E) Descriptors: cellular materials, flexible cellular materials, tests, determination, permeability, air flow. yright International Organization for Standardization Price based on 7 pages d without license from IHS Not for Resale Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of developing International Standards is carried out through Iso technical committees. Every member body interested in a subject for which a technical committee has been authorized 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. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. International Standard ISO 4638 was developed by Technical Committee ISO/TC 45, Rubber and rubber products, and was circulated to the member bodies in February 1982. It has been approved by the member bodies of the following countries: Austria Germany, F.R. Romania Belgium India South Africa, Rep. of Brazil Indonesia Spain Canada Ireland Sri Lanka China Mexico Thailand Czechoslovakia Netherlands Turkey Denmark Nigeria USA. Egypt, Arab Rep. of Poland USSR France Portugal The member body of the following country expressed disapproval of the document on technical grounds : United Kingdom @ International Organization for Standardization, 1984 Printed in Switzerland Copyright International Organization for Standardization No reproduction or networking permitted without license from IHS Not for Resale INTERNATIONAL STANDARD ISO4638-1984 (E) Polymeric materials, cellular flexible - Determination of air flow permeability 0 Introduction 3 Principle The air flow permeability of cellular materials indicates, in an Passing air under controlled conditions through atest piece in indirect manner, some of their structural properties. It may be the form of a cylinder or parailelepiped.Measurement of the used to establish correlations between the structure of these pressure drop between the two free faces of the test piece. materials and some of their physical properties. It also enables identification of the modifications to cellular structures pro- duced by chemical agents used in foaming, for example Symbols and terminology catalysts or surfactants. This International Standard is, therefore, useful for two pur- 4.1 Air flow permeability, K, is given by Darcy's law (see poses: figure 1), which describes the air flow in a homogeneous and isotropic (see note 1) porous medium under laminar flow condi- a)in studying the structure of cellular products in connec- tions(seenote2)bytheequation tion with their physical properties and their method of manufacture; qv K Ap b) in ensuring product quality (quality assurance). u= A ng NOTE -- Details of publications relating to flow behaviour in both where laminar and turbulent conditions are given in a bibliography. u is the linear air flow velocity, in metres per second; qy is the volumetric air flow rate, in cubic metres per Scope and field of application second, crossing the test piece; A is the right cross-sectional area, in square metres, of the This International Standard specifies a method for the deter- test piece; mination of the permeability of flexible cellular polymeric K is the flow permeability, in square metres, of the porous materials to air flow. medium; It is applicable to test piece