ISO INTERNATIONAL STANDARD 8841 First edition 1991-09-15 ANsl Internat Doc Sec Dense, shaped refractory products --. Determination of permeability to gases Produits réfractaires fagonneés denses Determination de la permeabilite aux gaz Reference number ISO 8841:1991(E) Copyright International Organization for Standardization Not for Resale ISO 8841:1991(E) Foreword Iso (the International Organization for Standardization) is a woridwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through 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, govern- mental and non-governmental, in liaison with Iso, also take part in the work. Iso collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnicail standardization Draft international standards adopted by the technical committees are circulated to the member bodies for voting. Pubication as an Inter- nationat Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard isO 8841 was prepared by Technical Committee ISO/TC 33, Refractories, Sub-Committee SC 2, Methods of testing. C 1SO1991 All rights reserved. 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 permisslon in writing from the publisher. International Organization for Standardization Case Postale 56.CH-1211 Genéve 20Switzerland Printed in Switzerland ii Copyright International Organization for Standardization Not for Resale ISO 8841:1991(E) Introduction distribution of the pores in the material and is therefore sensitive to variations in texture. It is not directly related to the apparent porosity and it shows a much greater variation than does porosity, both within a testpiece and between several pieces. It should also be noted that unlike density and porosity, permeability is a property that varies according to the direction in which the measure- the gas is flowing. The apparatus should not be influenced by air currents or by other to calised changes in temperature. IHS under Not for Resale itted without licensefrom IHS