ISO INTERNATIONAL 3448 STANDARD Second edition 1992-09-15 Industrial liquid lubricants --- IsO viscosity classification Classification Iso selonla viscosite Lubrifiants liquides industriels . Reference number ISO 3448:1992(E) CopyvihtIntematinal organizatin for Standardization dby IHS und Not for Resale king permitted without license from IHS ISO 3448:1992(E) Foreword 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 through iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be on that committee. International organizations, govern- represented 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 electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Inter- Standard requires approval by at least 75 % of the member national s bodies casting a vote. International Standard iso 3448 was prepared by Technical Committee IsO/TC 28, Petroleum products and lubricants. This second edition cancels and replaces the first edition (IsO 3448:1975), of which it constitutes a technical revision. Annex A of this international Standard is for information only. C ISO 1992 or by any means, electronic or mechanical, including photocopying and microfitm, withcut permission in writing from the publisher. International Organization for Standardization Case Postale 56· CH-1211 Geneve 20 · Switzerland Printed in Switzerland 11 Copyright International Organization for Standardization vithout license from IHS Not for Resale ISO 3448:1992(E) Introduction This International Standard has been prepared to meet the immediate needs of those Iso Technical Committees that promulgate International Standards for equipment and need to refer to lubricants, i.e. TC 39, Ma- chines tools; TC 123, Plain bearings: TC 131, Fluid power systems; and othcrs, by providing a classification of liquid lubricants according to viscosity grades. The purpose of this classification system is to establish a series of definite kinematic-viscosity levels so that lubricant suppliers, lubricant users and equipment designers will have a uniform and com- mon basis for designating or selecting industrial liquid lubricants ac- cording to the kinematic viscosity required in a particular application. When the first edition of this International Standard was being prepared, systems for classifying the viscosity characteristics of industrial liquid lubricants were simultaneously under study by the American Society for Testing and Materials (AsTM) in collaboration with the Society of Tribologists and Lubrication Engineers (STLE) (ASTM D 2422-68), by the British Standards Institution (BSl) (BS 4231) and by the Deutsches institut fur Normung (DIN). The cooperative effort first resulted in this isOclassificationin1975. It is desirable that any such classification system should cover the entire range of kinematic viscosities of liquid lubricants normally used; at the same time, the number of kinematic-viscosity grades within the classifi- cation should be limited. A continuous system, in which any lubricant within the viscosity range could be given a grade number, was first considered, but it was recognized that this would involve either an un- duly large number of grades or an unduly wide range of permitted kinematic viscosities for each grade. For the classification to be of direct use in engineering design calcu- lations, in which the kinematic viscosity of the lubricant is only one of the parameters, it is desirable that the viscosity grade width be not more than 10 % on either side of the nominal value. This would reflect an or-