ISO INTERNATIONAL STANDARD 8426 Second edition 2008-02-01 Hydraulic fluid power Positive displacement pumps and motors Determination of derived capacity Transmissions hydrauliques Pompes et moteurs volumetriques - Determinationdelacylindreemesuree Reference number X ISO 8426:2008(E) ISO @ ISO 2008 ISO 8426:2008(E) Contents Page 1 Scope 2 Normative references 3 Termsanddefinitions 4 Symbols and units 2 5 Test installation . 2 6 General test conditions .... 6 7 Test and evaluation procedures 8 8 Test report ....... 9 9 Identification statement (reference to this International Standard) 10 Annex A (normative) Measurement accuracy classes 11 Annex B (normative) Calculation of derived capacity using the zero-pressure intercept method .... 12 Bibliography 14 Iso 2008-All rights reserved ili IS0 8426:2008(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 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. 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 Standards. 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 this document may be the subject of patent Product testing. This second edition cancels and replaces the first edition (IsO 8426:1988), which has been technically revised. iv ISO 2008 - Allrights reserved ISO 8426:2008(E) Introduction enclosed circuit. Two types of components of such systems are the positive displacement pump and motor. One of the key performance parameters of these components is derived capacity, which is the volume of fluid displaced per shaft revolution. This International Standard is intended to unify test methods for determining the derived capacity of hydraulic fluid power positive displacement pumps and motors so as to enable the performance of differentcomponentstobe compared. @ ISO 2008 - All rights reserved V ISO 8426:2008(E) INTERNATIONAL STANDARD Hydraulic fluid power Positive displacement pumps and motors Determination of derived capacity 1 Scope This International Standard specifies the methods of determining the derived capacity of hydraulic fluid power positive displacement pumps and motors under steady-state conditions and at defined, continuous shaft rotational frequencies. Units can be tested as a positive displacement pump, with mechanical energy applied to the shaft and hydraulic connection and mechanical energy obtained at the shaft. NOTE Measurement accuracy is divided into three classes A, B and C, which are explained in Annex A. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated (including any amendments) applies. ISsO 1219-1, Fluid power systems and components —Graphic symbols and circuit diagrams — Part 1: Graphic symbols forconventional use and data-processing applications Iso 3448, Industrial liquid lubricants—IsO viscosity classification Iso 44o9, Hydraulic fluid power— Positive-displacement pumps, motors and integral transmissions Methods of testing and presenting basic steady state performance Iso 5598, Fluid power systems and components — Vocabulary IsO 6743-4, Lubricants, industrial oils and related products (class L)- Classification — Part 4: Family H (Hydraulic systems) 3 Terms and definitions For the purposes of this document, the terms and definitions given in IsO 5598 and the following apply. 3.1 direction of rot