NTERNATIONAL STANDARD TSO 3939 INTERNATIONALORGANIZATION FOR STANDARDIZATION-MEXKCAYHAPOAHAR OPTAHH3ALIMG TIO CTAHJAPTH3ALMW-ORGANISATION INTERNATIONALE DE NORMALISATION Fluid powersystems and components-Multiple lip packing sets -Methods for measuring stack heights Transmissions hydrauliques et pneumatiques-Garnitures a levres multiples -Methodes de mesurage des hauteurs d'empilage First edition-1977-03-15 UDC 621.8.032 Ref.No.ISO 3939-1977 (E) Descriptors:pneumatic equipment, hydraulic equipment,fluid power, dimensional measurement, seals (stoppers). Pricebasedon 4pages FOREWORD ISo (the International Organization for Standardization)is a worldwidefederation of national standards institutes (IsO member bodies).The work of developing International Standards is carried out throughisO technical committees.Every member body interested in a subject for which a technical committee has been set up 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 StandardsbytheIsoCouncil. International StandardISO3939 wasdevelopedbyTechnical Committee ISO/Tc131,Fluidpower systemsandcomponents,andwas circulatedto the memberbodiesinOctober1975. It hasbeen approved bythememberbodies ofthefollowing countries: Australia India Spain Austria ueder Sweden Belgium Korea, Dem. P.Rep.of Turkey Brazil Mexico UnitedKingdom Czechoslovakia Netherlands U.S.A. Finland Poland Yugoslavia France Romania Germany South Africa, Rep.of Nomemberbodyexpresseddisapprovalofthedocument. ? International Organization forStandardization,1977 Printed in Switzerland Copvriaht Intemational Organization for Standardization ISO 3939-1977 (E) INTERNATIONALSTANDARD Fluid power systems and components - Multiple lip packing sets - Methods for measuring stack heights INTRODUCTION This International Standard also specifies methods sfor measuring stack height of multiple lippacking sets in order Influidpowersystems,power istransmittedand controlled that both supplier and user can determine that the sets are through a fluid (liquid or gas) under pressure within an toan acceptabledimensional standard. enclosed circuit. Packing sets are used to contain the press- urized fluid within components with movable elements. It is not the intention of this International Standard to specifythedimensionsforpacking sets ortheircomponents Various methods are currently being used by different since such dimensions depend on the material being used, suppliers and users to measure the stack height of packing on the section and on thetype of design. sets. This frequently results in different values being ob- tained, owing to the nature of the materials used for seals and to the fact that a number of individual sealing rings are being measured together.Traditional measuring tools (for 2 REFERENCE example sliding calipers) cannot be accurately applied in ISO 5598, Fluid power-Vocabulary.1) such circumstances. In addition, results are greatly influ enced by the ability of the individual inspector. Cylinder,valveandpumpdesigners,quality controlperson- 3 DEFINITIONS nel,and inspection personnel need accurate stack height Fordefinitionsof termsused,see iso5598. dimensions of multiple lip packing sets to do their work effectively.By having these dimensions, users and sup- pliers canwork from a standard basewhen communicating GENERAL seal requirements.Inspection upon receipt is facilitated for the user,as is final inspection for the supplier; and both 4.1 This International Standard describes three acceptable have the opportunity of ensuringunderstanding concerning methods for determining the stack height of a multiple lip what has been received and what has been supplied.Having packing set. Each method has distinct advantages and disad- these dimensions