1、BSI Standards Publication BS ISO 6358-2:2013 Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 2: Alternative test methodsBS ISO 6358-2:2013 BRITISH STANDARD National foreword This British Standard is the UK implementation of ISO 6358-2:201
2、3. Together with BS ISO 6358-1:2013 and BS ISO 6358-3, it supersedes BS 7294:1990 (dual numbered as ISO 6358:1989), which will be withdrawn on publication of Part 3. The UK participation in its preparation was entrusted by Technical Committee MCE/18, Fluid power systems and components, to Subcommitt
3、ee MCE/18/-/5, Control components. A list of organizations represented on this subcommittee 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. The British Standards I
4、nstitution 2013. Published by BSI Standards Limited 2013 ISBN 978 0 580 61665 5 ICS 23.100.01 Compliance with a British Standard cannot confer immunity from legal obligations. This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2013.
5、Amendments/corrigenda issued since publication Date Text affectedBS ISO 6358-2:2013 ISO 2013 Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 2: Alternative test methods Transmissions pneumatiques Dtermination des caractristiques de dbit d
6、es composants traverss par un fluide compressible Partie 2: Mthodes dessai alternatives INTERNATIONAL STANDARD ISO 6358-2 First edition 2013-05-01 Reference number ISO 6358-2:2013(E)BS ISO 6358-2:2013ISO 6358-2:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights r
7、eserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either
8、 ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in SwitzerlandBS ISO 6358-2:2013ISO 6358-2:2013(E) ISO 2013 All rights
9、reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 2 3 Terms and definitions . 2 4 Symbols and units . 2 5 Test installation . 2 5.1 Test circuit for discharge test . 3 5.2 Test circuit for charge test . 3 5.3 General requirements . 4 5.4 Requirements for the ta
10、nk (item 4) 5 5.5 Special requirements . 7 6 Test procedures . 8 6.1 Test conditions 8 6.2 Measuring procedures 9 6.3 Calculation of characteristics 12 7 Presentation of test results 16 8 Identification statement (reference to this part of ISO 6358) 17 Annex A (informative) Evaluation of measurement
11、 uncertainty .18 Annex B (normative) Test method to determine and calibrate the volume of an isothermal tank .24 Annex C (informative) Isothermal tank stuffing 30 Annex D (informative) Test method to determine isothermal performance 33 Annex E (informative) Equations for calculation of flow-rate cha
12、racteristics .36 Annex F (informative) Procedures for calculating critical back-pressure ratio, b, and subsonic index, m, by the least-square method using the Solver function in Microsoft Excel .39 Bibliography .43BS ISO 6358-2:2013ISO 6358-2:2013(E) Foreword ISO (the International Organization for
13、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 r
14、ight 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. Internation
15、al 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
16、 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 rights. ISO shall not be held responsible for identifying any or all such patent rights. IS
17、O 6358-2 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 5, Control products and components. This first edition of ISO 6358-2, together with ISO 6358-1 and ISO 6358-3, cancels and replaces ISO 6358:1989, which has been technically revised. However, ISO 6358-2 and
18、 ISO 6358-3 are new standards whose scopes were not included in ISO 6358:1989. ISO 6358 consists of the following parts, under the general title Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids: Part 1: General rules and test methods for steady
19、-state flow Part 2: Alternative test methods Part 3: Method for calculating steady-state flow-rate characteristics of assembliesiv ISO 2013 All rights reservedBS ISO 6358-2:2013ISO 6358-2:2013(E) Introduction In pneumatic fluid power systems, power is transmitted and controlled through a gas under p
20、ressure within a circuit. Components that make up such a circuit are inherently resistive to the flow of the gas and it is necessary, therefore, to define and determine the flow-rate characteristics that describe their performance. ISO 6358:1989 was developed to determine the flow-rate characteristi
21、cs of pneumatic valves, based upon a model of converging nozzles. The method included two characteristic parameters: sonic conductance, C, and critical pressure ratio, b, used in a proposed mathematical approximation of the flow behaviour. The result described flow performance of a pneumatic valve f
22、rom choked flow to subsonic flow, based on static pressure. This new edition uses stagnation pressure instead, to take into account the influence of flow velocity on the measurement of pressures. Experience has demonstrated that many pneumatic valves have convergingdiverging characteristics that do
23、not fit the ISO 6358:1989 model very well. Furthermore, new developments have allowed the application of this method to additional components beyond pneumatic valves. However, this now requires the use of four parameters (C, b, m, and p c ) to define the flow performance in both the choked and subso
24、nic flow regions. This part of ISO 6358 describes a set of three flow-rate characteristic parameters determined from test results. These parameters are described as follows and are listed in decreasing order of priority: The sonic conductance, C, corresponding to the maximum flow rate (choked) is th
25、e most important parameter. This parameter is defined by the upstream stagnation conditions. The critical back-pressure ratio, b, representing the boundary between choked and subsonic flow is second in importance. Its definition differs here from the one in ISO 6358:1989 because it corresponds to th
26、e ratio of downstream to upstream stagnation pressures. The subsonic index, m, is used if necessary to represent more accurately the subsonic flow behaviour. For components with a fixed flow path, m is distributed around 0,5. In these cases, only the first two characteristic parameters C and b are n
27、ecessary. For many other components, m will vary widely. In these cases, it is necessary to determine C, b, and m. Several changes to the test equipment were made to overcome apparent violations of the theory of compressible fluid flow. This included expanded inlet pressure-measuring tubes to satisf
28、y the assumptions of negligible inlet velocity to the item under test and to allow the inlet stagnation pressure to be measured directly. Expanded outlet tubes allow the direct measurement of downstream stagnation pressure to better accommodate the different component models. The difference between
29、stagnation pressure at upstream and downstream of component means a loss of pressure energy. ISO 6358-3 can be used to calculate without measurements an estimate of the overall flow-rate characteristics of an assembly of components and piping, using the characteristics of each component and piping d
30、etermined in accordance with this part of ISO 6358 or ISO 6358-1. The discharge and charge test methods specified in this part of ISO 6358 have the following advantages over the test method specified in ISO 6358-1: a) an air source with a large flow-rate capacity is not required; b) components with
31、larger flow-rate capacity can be tested more easily; c) energy consumption is minimised; and d) test time is shortened in the discharge test, and noise level is decreased in the charge test. It should be noted that performance characteristics measured in accordance with this edition of ISO 6358 will
32、 differ from those measured in accordance with ISO 6358:1989. ISO 2013 All rights reserved vBS ISO 6358-2:2013BS ISO 6358-2:2013Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 2: Alternative test methods 1 Scope This part of ISO 6358 spec
33、ifies a discharge test and a charge test as alternative methods for testing pneumatic fluid power components that use compressible fluids, i.e. gases, and that have internal flow passages that can be either fixed or variable in size to determine their flow-rate characteristics. However, this part of
34、 ISO 6358 does not apply to components whose flow coefficient is unstable during use, i.e. components that exhibit remarkable hysteretic behaviour (because they can contain flexible parts that deform under the flow) or that have an internal feedback phenomenon (such as regulators), or components tha
35、t have a cracking pressure such as non-return (check) valves and quick-exhaust valves. In addition, it does not apply to components that exchange energy with the fluid during flow-rate measurement, e.g. cylinders, accumulators, etc. NOTE This part of ISO 6358 does not provide a method to determine i
36、f a component has hysteretic behaviour; ISO 6358-1 does provide such a method. Table 1 provides a summary of which parts of ISO 6358 can be applied to various components. Table 1 Application of ISO 6358 test methods to components Components Constant upstream pressure test Variable upstream pressure
37、test ISO 6358-1 constant upstream pressure test ISO 6358-2 charge test ISO 6358-1 variable upstream pressure test ISO 6358-2 discharge test Group 1 Directional control valves yes yes yes yes Flow control valves yes yes yes yes Connectors yes yes yes yes Valve manifolds yes yes yes yes Group of compo
38、nents yes yes yes yes Group 2 Filters and lubricators yes no no no Non-return (check) valves yes no no no Tubes and hoses yes no no no Group 3 Silencers and exhaust oil mist separators no no yes yes Blow nozzles no no yes yes Quick-exhaust valves no no yes yes Cylinder end heads no no yes yes The ch
39、arge test cannot be performed on components that do not have downstream port connections. This part of ISO 6358 specifies requirements for the test installation, the test procedure, and the presentation of results. INTERNATIONAL ST ANDARD ISO 6358-2:2013(E) ISO 2013 All rights reserved 1BS ISO 6358-
40、2:2013ISO 6358-2:2013(E) Evaluation of measurement uncertainties is described in Annex A. Requirements for a method to test the volume of an isothermal tank are given in Annex B. Guidance on the isothermal tank is given in Annex C. Requirements for a method to test isothermal performance are given i
41、n Annex D. Guidance on the equation for calculating characteristics is given in Annex E. Guidance on calculating flow-rate characteristics is given in Annex F. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for i
42、ts application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1219-1, Fluid power systems and components Graphical symbols and circuit diagrams Part 1: Graphical symbols for conventi
43、onal use and data-processing applications ISO 5598, Fluid power systems and components Vocabulary ISO 6358-1, Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 1: General rules and test methods for steady-state flow 3 Terms and definitions
44、For the purposes of this document, the terms and definitions in ISO 5598 and ISO 6358-1 apply. 4 Symbols and units 4.1 The symbols and units shall be in accordance with ISO 6358-1 and Table 2. Table 2 Symbols and units Reference Description Symbol Dimension a SI units Practical units 5.5.2 Time t T
45、s s 5.4.3 Tank volume V L 3 m 3 dm 3 aT = time; L = length 4.2 The numerals used as subscripts to the symbols shall be in accordance with ISO 6358-1 and Table 3. Table 3 Subscripts Subscript Meaning 3 Tank conditions 4.3 The graphic symbols used in Figures 1 and 2 are in accordance with ISO 1219-1.
46、5 Test installation CAUTION Figures 1 and 2 illustrate basic circuits that do not incorporate all the safety devices necessary to protect against damage in the event of component failure. It is important that those responsible for carrying out the test give due consideration to safeguarding both per
47、sonnel and equipment.2 ISO 2013 All rights reservedBS ISO 6358-2:2013ISO 6358-2:2013(E) 5.1 Test circuit for discharge test A suitable test circuit as shown in Figure 1 shall be used for the discharge test. See 5.3.5. p 3p 1p 21 2 3 4 13 7 12 9 8 14 15 16 11 5 610NOTE See Table 4 for the key to test
48、 circuit components. Figure 1 Test circuit for discharge test 5.2 Test circuit for charge test A suitable test circuit as shown in Figure 2 shall be used for the charge test.17 13 7 69 8 14 15 11 12 18 3 4 16 p 3p 2p 110 5 NOTE See Table 4 for the key to test circuit components. Figure 2 Test circui
49、t for charge test ISO 2013 All rights reserved 3BS ISO 6358-2:2013ISO 6358-2:2013(E) Table 4 Key to test circuit components shown in Figures 1 and 2 Key item number Relevant subclause or paragraph Description Additional requirements 1 5.3.2 Compressed gas source and filter for discharge test 2 - Adjustable pressure regulator for discharge test 3 - Shut-off valve 4 5.4 Tank 5 - Temperature-measuring instrument 6 5.3.7 Upstream pressure-measuring tube 7 5.3.7 Upstream transition connector 8 - Component
