1、BRITISH STANDARD BS ISO 8426:2008 Hydraulic fluid power Positive displacement pumps and motors Determination of derived capacity ICS 23.100.10 BS ISO 8426:2008 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 February 2008 BSI 2008 ISBN 978
2、 0 580 55035 5 National foreword This British Standard is the UK implementation of ISO 8426:2008. It supersedes BS 7250:1989 which is withdrawn. The UK participation in its preparation was entrusted by Technical Committee MCE/18, Fluid power systems and components, to Panel MCE/18/-/8, Product testi
3、ng. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity
4、 from legal obligations. Amendments/corrigenda issued since publication Date CommentsINTERNATIONAL STANDARD ISO 8426 Second edition 2008-02-01 Reference number ISO 8426:2008(E) Hydraulic fluid power Positive displacement pumps and motors Determination of derived capacity Transmissions hydrauliques P
5、ompes et moteurs volumtriques Dtermination de la cylindre mesureBS ISO 8426:2008ii iii Contents Page 1 Scope 1 2 Normative references 1 3 Terms and definitions 1 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 Identif
6、ication 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 BS ISO 8426:2008iv Foreword ISO (the International Organization for St
7、andardization) 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 rig
8、ht to be represented on that committee. International organizations, governmental 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. International
9、 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 a
10、n 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 rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO
11、8426 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 8, Product testing. This second edition cancels and replaces the first edition (ISO 8426:1988), which has been technically revised. BS ISO 8426:2008v Introduction In hydraulic fluid power systems, power is tran
12、smitted and controlled through a liquid under pressure within an 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 rev
13、olution. 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 different components to be compared. BS ISO 8426:2008blank1 Hydraulic fluid power Positive di
14、splacement pumps and motors Determination of derived capacity 1S c o p e 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 fre
15、quencies. Units can be tested as a positive displacement pump, with mechanical energy applied to the shaft and hydraulic energy obtained at the outlet fluid connection, or as a motor, with hydraulic energy supplied to the inlet fluid connection and mechanical energy obtained at the shaft. NOTE Measu
16、rement 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 references, only the edition cited applies. For undated references, the latest edition
17、 of the referenced document (including any amendments) applies. ISO 1219-1, Fluid power systems and components Graphic symbols and circuit diagrams Part 1: Graphic symbols for conventional use and data-processing applications ISO 3448, Industrial liquid lubricants ISO viscosity classification ISO 44
18、09, 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
19、 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 rotation direction of rotation as viewed looking at the shaft end NOTE In cases where doubt exists, a sketch should be pro
20、vided. 3.2 volume flow rate volume of fluid crossing the transverse plane of a flow path per unit of time BS ISO 8426:20082 3.3 derived capacity volume of fluid displaced by a pump or motor per shaft revolution, calculated from measurements at different outlet pressures (for pumps) or inlet pressure
21、s (for motors) under specified test conditions 4 Symbols and units The symbols and units used throughout this International Standard are shown in Table 1. The graphic symbols used throughout this standard are in accordance with the requirements of ISO 1219-1. 5 Test installation 5.1 General 5.1.1 Pr
22、e-test condition Before the test begins, the unit under test shall be run-in in accordance with the manufacturers recommendation. 5.1.2 Installation The test installation shall be designed to prevent air entrainment and precautions shall be taken to remove all free air from the system before beginni
23、ng the test. The unit under test shall be installed and operated in the test circuit (see 5.2) in accordance with the manufacturers operating instructions. The inlet tube to the unit under test shall be straight, shall have a uniform bore and shall have dimensions consistent with the dimensions of t
24、he units inlet connection. Table 1 Symbols and units Symbol Description Unit Dimension a Internal diameter of tube m b Rotational frequency (speed) r/min b Pressure MPa (bar) c b Volume flow rate l/min d b Effective flow rate l/min b Derived capacity l/r b Temperature Kinematic viscosity Mass densit
25、y amass; length; time; temperature. b Letter symbol is used in accordance with ISO 4391. c . d . d L n t 1 p mL 1 t 2 q V L 3 t 1 q V ,e L 3 t 1 V i L 3 C v m 2 /s L 2 t 1 kg/m 3 mL 3 m = L = t = = 1 bar = 10 5 Pa = 0,1 MPa; 1 Pa = 1N / m 2 1l = 1d m 3 BS ISO 8426:20083 5.1.3 Test fluid cleanliness
26、The cleanliness of the test fluid shall be in accordance with the recommendation of the manufacturer of the unit under test. Filters of sufficient number and of an appropriate type shall be installed in the test circuit to provide the necessary test fluid cleanliness. Details of any filtration used
27、in the test circuit shall be stated in the test report. 5.2 Test circuits 5.2.1 General Figures 1, 2 and 3 illustrate the basic test circuits. These circuits do not incorporate all of the necessary safety devices. It is important that those responsible for carrying out the tests give consideration t
28、o safeguarding personnel and equipment. 5.2.2 Circuits for testing positive displacement pumps Either an open-circuit test circuit in accordance with Figure 1 or a closed-circuit test circuit in accordance with Figure 2 shall be used. If a pressurized inlet condition is required, a pressure control
29、valve shall be provided in the inlet tube at a point not less than from the pressure measuring point. If it is necessary to increase the inlet pressure to the unit under test, this may be accomplished by providing a) a boost pump and a pressure-relief valve capable of maintaining the pressure at the
30、 inlet of the unit under test at the desired pressure; NOTE When a closed test circuit (see Figure 2) is used, unless a higher flow rate is required for cooling purposes, it is necessary that the boost pump supply a flow rate slightly in excess of the total flow-rate losses of the circuit. b) a mean
31、s other than a boost pump (e.g. an air-loaded tank or pressurized reservoir); if these are used, precautions shall be taken to minimize the effects of entrained or dissolved air in the test circuit. 5.2.3 Circuit for testing positive displacement motors A test circuit incorporating a controlled flow
32、 source similar to that shown in Figure 3 shall be used. 10d BS ISO 8426:20084 Key 1 temperature-measuring device 2 pressure-measuring device 3 unit under test 4 integrating flow meter 5 pressure control valve 6 temperature controller 7 integrating flow meter (alternative position) NOTE 1 See 6.6 fo
33、r the location of pressure and temperature measuring points. NOTE 2 The part of the circuit shown with dashed lines is used only if the unit under test requires a casing drain. Figure 1 Open-circuit test circuit for pumps BS ISO 8426:20085 Key 1 temperature-measuring device 2 pressure-measuring devi
34、ce 3b o o s t p u m p 4 pressure control valve (4a and 4b) 5 integrating flow meter 6 unit under test 7 temperature controller 8 integrating flow meter (alternative position) NOTE 1 See 6.6 for the location of pressure and temperature measuring points. NOTE 2 The part of the circuit shown with dashe
35、d lines is used only if the unit under test requires a casing drain. Figure 2 Closed-circuit test circuit for pumps BS ISO 8426:20086 6 General test conditions 6.1 Test fluid Only a fluid approved by the manufacturer of the unit under test shall be used during testing and the test fluid used shall b
36、e stated in the test report. The kinematic viscosity, , and the mass density, , of the test fluid shall be recorded for the controlled temperature used during the test. 6.2 Test temperatures Tests shall be carried out at fluid temperatures within the range recommended by the manufacturer of the unit
37、 under test. The temperature of the test fluid and the ambient temperature shall be maintained within the limits specified in Table 2. Key 1 controlled flow source 2 integrating flow meter 3 temperature-measuring device 4 pressure-measuring device 5 unit under test 6 pressure control valve 7 integra
38、ting flow meter (alternative position) NOTE See 6.6 for the location of pressure and temperature measuring points. Figure 3 Test circuit for motors v BS ISO 8426:20087 As a minimum, the following shall be recorded for each test condition: a) test fluid temperature at the inlet of the unit under test
39、; b) test fluid temperature at the outlet of the unit under test; c) test fluid temperature at the flow rate measurement point; d) ambient test area temperature. 6.3 Casing pressure If the casing pressure (i.e. the fluid pressure within the casing of the unit under test) affects its performance, the
40、 casing pressure used during testing shall be maintained at a value recommended by the manufacturer and that value shall be recorded in the test report. 6.4 Steady-state conditions Each set of measurements shall be taken only when the values of the controlled parameters are within the limits given i
41、n Table 2. 6.5 Volume flow rate The volume flow rate of the test unit shall be measured adjacent to the motor inlet port, , or pump outlet port, , as appropriate, and the corresponding test fluid temperature and pressure shall be recorded. 6.6 Pressure and temperature measuring point locations Press
42、ure measuring points shall be located in the tubes adjacent to the unit under test and no less than and no more than from the port face of the unit. Temperature measuring points shall be located in the tubes adjacent to the pressure measuring points, no less than and no more than from the correspond
43、ing pressure measuring point and further removed from the unit under test. Greater distances may be used provided consideration is given to the effect of pressure losses in the tube. Table 2 Limits of permissible variation in the value of controlled parameters during a specified test condition Contr
44、olled parameter Limits of permissible variation in the value of controlled parameters for each class of measurement accuracy ABC Rotational frequency ( ) Flow rate ( ) Pressure, MPa (bar) gauge where (1,5) ( ) ( ) ( ) Pressure, MPa (bar) gauge where (1,5) ( ) ( ) ( ) Test fluid temperature ( ) Ambie
45、nt temperature ( ) a See Annex A. % 0,5 1 2 % 0,5 1,5 2,5 p 0,15 0,001 0,01 0,003 0,03 0,005 0,05 p 0,15 0,05 0,5 0,15 1,5 0,25 2,5 C 0,5 1 2 C 2,5 2,5 2,5 q V 1,e,m q V 2,e,p 2d 4d 2d 4d BS ISO 8426:20088 7 Test and evaluation procedures 7.1 General 7.1.1 This International Standard applies to unit
46、s that can be used either as hydraulic positive-displacement pumps or hydraulic positive-displacement motors. Units intended to be used as motors shall be tested as motors and units intended to be used as pumps shall be tested as pumps. The derived capacity determined when a given unit is tested as
47、a motor can differ from that determined when the unit is tested as a pump. 7.1.2 The number of readings taken and their disposition over the measurement range shall be selected so as to give a representative indication of the units performance over its full operating range. 7.1.3 If flow rate measur
48、ements are made at an alternative location and not at the port face of the unit under test (i.e. the pump outlet or motor inlet), the corresponding test fluid temperature and pressure at the alternative location shall be recorded and the flow rate at the alternative location corrected to reflect the
49、 flow rate at the port face of the unit under test. These corrections shall be made in accordance with procedures specified in ISO 4409. NOTE Flow rate corrections are necessary to compensate for differences in temperature and pressure between the port face of the unit under test and the alternative flow rate measurement locati
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