1、BSI Standards PublicationBS ISO 6358-2:2013Pneumatic fluid power Determination of flow-ratecharacteristics of componentsusing compressible fluidsPart 2: Alternative test methodsBS ISO 6358-2:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 6358-2:2013. Toge
2、therwith BS ISO 6358-1:2013 and BS ISO 6358-3, it supersedes BS 7294:1990 (dualnumbered as ISO 6358:1989), which will be withdrawn on publication ofPart 3.The UK participation in its preparation was entrusted by Technical Committee MCE/18, Fluid power systems and components, to SubcommitteeMCE/18/-/
3、5, Control components.A list of organizations represented on this subcommittee can beobtained on request to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application. The British Standards Institution 2013.
4、Published by BSI Standards Limited 2013ISBN 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 StandardsPolicy and Strategy Committee on 30 November 2013.Amendments/corrigenda
5、 issued since publicationDate Text affectedBS ISO 6358-2:2013 ISO 2013Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 2: Alternative test methodsTransmissions pneumatiques Dtermination des caractristiques de dbit des composants traverss p
6、ar un fluide compressible Partie 2: Mthodes dessai alternativesINTERNATIONAL STANDARDISO6358-2First edition2013-05-01Reference numberISO 6358-2:2013(E)BS ISO 6358-2:2013ISO 6358-2:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise specifi
7、ed, 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 ISO at the address below or ISOs
8、 member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 6358-2:2013ISO 6358-2:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntr
9、oduction v1 Scope .12 Normative references 23 Terms and definitions .24 Symbols and units .25 Test installation .25.1 Test circuit for discharge test . 35.2 Test circuit for charge test . 35.3 General requirements . 45.4 Requirements for the tank (item 4) 55.5 Special requirements . 76 Test procedur
10、es . 86.1 Test conditions 86.2 Measuring procedures 96.3 Calculation of characteristics 127 Presentation of test results 168 Identification statement (reference to this part of ISO 6358) 17Annex A (informative) Evaluation of measurement uncertainty .18Annex B (normative) Test method to determine and
11、 calibrate the volume of an isothermal tank .24Annex C (informative) Isothermal tank stuffing 30Annex D (informative) Test method to determine isothermal performance 33Annex E (informative) Equations for calculation of flow-rate characteristics .36Annex F (informative) Procedures for calculating cri
12、tical back-pressure ratio, b, and subsonic index, m, by the least-square method using the Solver function in Microsoft Excel .39Bibliography .43BS ISO 6358-2:2013ISO 6358-2:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
13、(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 represented on that committee. International organizations, g
14、overnmental 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 Standards are drafted in accordance with the rules given in the ISO/IE
15、C 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 membe
16、r 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 6358-2 was prepared by Technical Committee ISO/TC 131, Fluid power systems
17、, 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 ISO 6358-3 are new standards whose scopes were not included in ISO 6358:1989
18、.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-state flow Part 2: Alternative test methods Part 3: Method for calculating st
19、eady-state flow-rate characteristics of assembliesiv ISO 2013 All rights reservedBS ISO 6358-2:2013ISO 6358-2:2013(E)IntroductionIn pneumatic fluid power systems, power is transmitted and controlled through a gas under pressure within a circuit. Components that make up such a circuit are inherently
20、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 characteristics of pneumatic valves, based upon a model of converging nozzles. The method incl
21、uded 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 from choked flow to subsonic flow, based on static pressure. This new edition uses
22、 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 not fit the ISO 6358:1989 model very well. Furthermore, new developments have allo
23、wed the application of this method to additional components beyond pneumatic valves. However, this now requires the use of four parameters (C, b, m, and pc) to define the flow performance in both the choked and subsonic flow regions.This part of ISO 6358 describes a set of three flow-rate characteri
24、stic 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 the most important parameter. This parameter is defined by the upstream stagnation cond
25、itions. 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 the ratio of downstream to upstream stagnation pressures. The subsonic index, m, is use
26、d 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 necessary. For many other components, m will vary widely. In these cases, it is necess
27、ary 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 satisfy the assumptions of negligible inlet velocity to the item under test and to allow the
28、 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 stagnation pressure at upstream and downstream of component means a loss of pressure e
29、nergy.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 determined in accordance with this part of ISO 6358 or ISO 6358-1.The discharge and char
30、ge 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 larger flow-rate capacity can be tested more easily;c) energy consumption is minimised; an
31、dd) 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 differ from those measured in accordance with ISO 6358:1989. ISO 2013 All rights reserved vB
32、S ISO 6358-2:2013BS ISO 6358-2:2013Pneumatic fluid power Determination of flow-rate characteristics of components using compressible fluids Part 2: Alternative test methods1 ScopeThis part of ISO 6358 specifies a discharge test and a charge test as alternative methods for testing pneumatic fluid pow
33、er 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 ISO 6358 does not apply to components whose flow coefficient is unstable during use, i.e. comp
34、onents 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 that have a cracking pressure such as non-return (check) valves and quick-exhaust valves. In addit
35、ion, 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 if a component has hysteretic behaviour; ISO 6358-1 does provide such a method.Table 1 provides a
36、 summary of which parts of ISO 6358 can be applied to various components.Table 1 Application of ISO 6358 test methods to componentsComponentsConstant upstream pressure testVariable upstream pressure testISO 6358-1 constant upstream pressure testISO 6358-2 charge testISO 6358-1 variable upstream pres
37、sure testISO 6358-2 discharge testGroup 1 Directional control valves yes yes yes yesFlow control valves yes yes yes yesConnectors yes yes yes yesValve manifolds yes yes yes yesGroup of components yes yes yes yesGroup 2 Filters and lubricators yes no no noNon-return (check) valves yes no no noTubes a
38、nd hoses yes no no noGroup 3 Silencers and exhaust oil mist separatorsno no yes yesBlow nozzles no no yes yesQuick-exhaust valves no no yes yesCylinder end heads no no yes yesThe charge test cannot be performed on components that do not have downstream port connections.This part of ISO 6358 specifie
39、s requirements for the test installation, the test procedure, and the presentation of results.INTERNATIONAL STANDARD ISO 6358-2:2013(E) ISO 2013 All rights reserved 1BS ISO 6358-2:2013ISO 6358-2:2013(E)Evaluation of measurement uncertainties is described in Annex A. Requirements for a method to test
40、 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 in Annex D. Guidance on the equation for calculating characteristics is given in Annex E. Guidance on calculating flow-rate
41、characteristics is given in Annex F.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the refer
42、enced document (including any amendments) applies.ISO 1219-1, Fluid power systems and components Graphical symbols and circuit diagrams Part 1: Graphical symbols for conventional use and data-processing applicationsISO 5598, Fluid power systems and components VocabularyISO 6358-1, Pneumatic fluid po
43、wer Determination of flow-rate characteristics of components using compressible fluids Part 1: General rules and test methods for steady-state flow3 Terms and definitionsFor the purposes of this document, the terms and definitions in ISO 5598 and ISO 6358-1 apply.4 Symbols and units4.1 The symbols a
44、nd units shall be in accordance with ISO 6358-1 and Table 2.Table 2 Symbols and unitsReference Description Symbol Dimension aSI units Practical units5.5.2 Time t T s s5.4.3 Tank volume V L3m3dm3aT = time; L = length4.2 The numerals used as subscripts to the symbols shall be in accordance with ISO 63
45、58-1 and Table 3.Table 3 SubscriptsSubscript Meaning3 Tank conditions4.3 The graphic symbols used in Figures 1 and 2 are in accordance with ISO 1219-1.5 Test installationCAUTION Figures 1 and 2 illustrate basic circuits that do not incorporate all the safety devices necessary to protect against dama
46、ge in the event of component failure. It is important that those responsible for carrying out the test give due consideration to safeguarding both personnel and equipment.2 ISO 2013 All rights reservedBS ISO 6358-2:2013ISO 6358-2:2013(E)5.1 Test circuit for discharge testA suitable test circuit as s
47、hown in Figure 1 shall be used for the discharge test. See 5.3.5.p3p1p21 2 3 4 13 7 12 9 8 14 15 16 11 5 610NOTE See Table 4 for the key to test circuit components.Figure 1 Test circuit for discharge test5.2 Test circuit for charge testA suitable test circuit as shown in Figure 2 shall be used for t
48、he charge test.17 13 7 69 8 14 15 11 12 18 3 4 16 p3p2p110 5 NOTE See Table 4 for the key to test circuit components.Figure 2 Test circuit 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 2Key item numberR
49、elevant subclause or paragraphDescription Additional requirements1 5.3.2Compressed gas source and filter for discharge test2 -Adjustable pressure regulator for discharge test3 - Shut-off valve4 5.4 Tank5 - Temperature-measuring instrument6 5.3.7 Upstream pressure-measuring tube7 5.3.7 Upstream transition connector8 - Component under test9 5.3.7 Downstream transition connector10 5.3.7 Downstream pressure-measuring tube11 5.3.10 Pressure transducer12 5.3.10 Pressure transducer13 5.3.4 and 5.3.9 Flow control solenoid
