1、BSI Standards PublicationBS EN ISO 4126-7:2013Safety devices for protectionagainst excessive pressurePart 7: Common dataCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO
2、4126-7:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 4126-7:2013. It supersedes BS EN ISO 4126-7:2003 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PSE/18/6, Industrial valves, steam traps, actuators a
3、nd safety devices against excessive pressure - Safety devices against excessive pressure.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 fo
4、r its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013ISBN 978 0 580 66506 6 ICS 13.240 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy
5、 and Strategy Committee on 31 July 2013.Amendments issued since publicationDate T e x t a f f e c t e dCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-EUROPEAN STANDARD NORME EUR
6、OPENNE EUROPISCHE NORM EN ISO 4126-7 July 2013 ICS 13.240 Supersedes EN ISO 4126-7:2004English Version Safety devices for protection against excessive pressure - Part 7: Common data (ISO 4126-7:2013) Dispositifs de scurit pour protection contre les pressions excessives - Partie 7: Donnes communes (I
7、SO 4126-7:2013) Sicherheitseinrichtungen gegen unzulssigen berdruck - Teil 7: Allgemeine Daten (ISO 4126-7:2013) This European Standard was approved by CEN on 25 April 2013. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europ
8、ean Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions
9、 (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Bel
10、gium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switz
11、erland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. R
12、ef. No. EN ISO 4126-7:2013: ECopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 4126-7:2013EN ISO 4126-7:2013 (E) 3 Foreword This document (EN ISO 4126-7:2013) has been pr
13、epared by Technical Committee ISO/TC 185 “Safety devices for protection against excessive pressure“ in collaboration with the Technical Committee CEN/TC 69 “Industrial valves” the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either b
14、y publication of an identical text or by endorsement, at the latest by January 2014, and conflicting national standards shall be withdrawn at the latest by January 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or C
15、ENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 4126-7:2004. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU
16、Directive. For relationship with EU Directive, see informative Annex ZA, which is an integral part of this document. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bul
17、garia, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, T
18、urkey and the United Kingdom. Endorsement notice The text of ISO 4126-7:2013 has been approved by CEN as EN ISO 4126-7:2013 without any modification. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without l
19、icense from IHS-,-,-BS EN ISO 4126-7:2013EN ISO 4126-7:2013 (E) 4 Annex ZA (informative) Relationship between this European Standard and the Essential Requirements of EU Directive 97/23/EC (PED) This European Standard has been prepared under a mandate given to CEN by the European Commission and the
20、European Free Trade Association to provide one means of conforming to Essential Requirements of the New Approach Directive 97/23/EC (PED). Once EN ISO 4126-7 is cited in the Official Journal of the European Communities under that Directive and has been implemented as a national standard in at least
21、one Member State, compliance with the normative clauses of EN ISO 4126-7 confers, within the limits of the scope of EN ISO 4126-7, a presumption of conformity with the corresponding Essential Requirements of that Directive and associated EFTA regulations. Table ZA.1 Correspondence between this Europ
22、ean Standard and Directive 97/23/EC (PED) Sub-clauses of this EN Essential Requirements of Directive 97/23/EC (PED) Essential Requirements Annex I of PED 5 and 6 Pressure Limitations 2.11.1 WARNING Other requirements and other EU Directives may be applicable to the product(s) falling within the scop
23、e of EN ISO 4126-7. Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 4126-7:2013ISO 4126-7:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 N
24、ormative references 13 Terms and definitions . 14 Symbols and units . 35 Determination of safety valve performance 45.1 Determination of coefficient of discharge . 45.2 Critical and subcritical flow . 45.3 Discharge capacity at critical flow . 45.4 Discharge capacity for any gas at subcritical flow
25、55.5 Discharge capacity for non-flashing liquid as the test medium in the turbulent zone where the Reynolds number Re is equal to or greater than 80 000 56 Sizing of safety valves 66.1 General . 66.2 Valves for gas or vapour relief . 66.3 Calculation of capacity 67 Thermodynamic properties . 87.1 St
26、eam data. 87.2 Value of C as a function of k 87.3 Theoretical capacity correction factors for sub-critical flow (Kb) . 87.4 Estimating chart for compressibility factor, Z .197.5 Capacity correction factor for viscosity, Kv.217.6 Properties of gases 228 Minimum requirements for helical compression sp
27、rings 238.1 General 238.2 Materials 238.3 Marking 238.4 Dimensions 248.5 Spring plates/buttons 248.6 Inspection, testing and tolerances 249 Minimum requirements for safety valve disc springs 279.1 General 279.2 Materials 279.3 Marking 279.4 Dimensions 279.5 Inspection, testing and tolerances 27Annex
28、 A (informative) Examples of capacity calculations for various media 28Bibliography .33Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS EN ISO 4126-7:2013ISO 4126-7:2013(E)Fore
29、wordISO (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 technical committees. Each member body interested in a subject for which a techni
30、cal committee has been established 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. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of e
31、lectrotechnical 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 th
32、e 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 rights. ISO shall not be held responsible for iden
33、tifying any or all such patent rights.ISO 4126-7 was prepared by Technical Committee ISO/TC 185, Safety devices for protection against excessive pressure.This second edition cancels and replaces the first edition (ISO 4126-7:2004), which has been technically revised. It also incorporates the Technic
34、al Corrigendum ISO 4126-7:2004/Cor.1:2006.ISO 4126 consists of the following parts, under the general title Safety devices for protection against excessive pressure: Part 1: Safety valves Part 2: Bursting disc safety devices Part 3: Safety valves and bursting disc safety devices in combination Part
35、4: Pilot-operated safety valves Part 5: Controlled safety pressure relief systems (CSPRS) Part 6: Application, selection and installation of bursting disc safety devices Part 7: Common data Part 9: Application and installation of safety devices excluding stand-alone bursting disc safety devices Part
36、 10: Sizing of safety valves for gas/liquid two-phase flow Part 11: Performance testing1)1) Under preparation.iv ISO 2013 All rights reservedCopyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license fr
37、om IHS-,-,-BS EN ISO 4126-7:2013INTERNATIONAL STANDARD ISO 4126-7:2013(E)Safety devices for protection against excessive pressure Part 7: Common data1 ScopeThis part of ISO 4126 specifies requirements for safety valves. It contains information which is common to ISO 4126-1 to ISO 4126-6 to avoid unn
38、ecessary repetition.For flashing liquids or two-phase mixtures, see ISO 4126-10.The user is cautioned that it is not recommended to use the ideal gas formula presented in 6.3 when the relieving temperature is greater than 90 % of the thermodynamic critical temperature and the relieving pressure is g
39、reater than 50 % of the thermodynamic critical pressure. Additionally, condensation is not considered. If condensation occurs, the method presented in 6.3 should not be used.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indisp
40、ensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 4126-1, Safety devices for protection against excessive pressure Part 1: Safety valvesISO 4126-2, Safety dev
41、ices for protection against excessive pressure Part 2: Bursting disc safety devicesISO 4126-4, Safety devices for protection against excessive pressure Part 4: Pilot operated safety valvesISO 4126-5, Safety devices for protection against excessive pressure Part 5: Controlled safety pressure relief s
42、ystems (CSPRS)3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 4126-1, ISO 4126-2, ISO 4126-4 ISO 4126-5 and the following apply.NOTE Pressure unit used in ISO 4126-7 is the bar (1 bar = 105Pa), quoted as gauge (relative to atmospheric pressure) or abs
43、olute as appropriate.3.1safety valvevalve which automatically, without the assistance of any energy other than that of the fluid concerned, discharges a quantity of the fluid so as to prevent a predetermined safe pressure being exceeded, and which is designed to re-close and prevent further flow of
44、fluid after normal pressure conditions of service have been restoredNote 1 to entry: The valve can be characterized either by pop action (rapid opening) or by opening in proportion (not necessarily linear) to the increase in pressure over the set pressure. The use of the term safety valve in this pa
45、rt of ISO 4126 applies to other valve types as covered in ISO 4126-1, ISO 4126-4 and ISO 4126-5. ISO 2013 All rights reserved 1Copyright European Committee for Standardization Provided by IHS under license with CENNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-BS
46、EN ISO 4126-7:2013ISO 4126-7:2013(E)3.2set pressurepredetermined pressure at which a safety valve under operating conditions commences to openNote 1 to entry: It is the gauge pressure measured at the valve inlet at which the pressure forces tending to open the valve for the specific service conditio
47、ns are in equilibrium with the forces retaining the valve disc on its seat.3.3maximum allowable pressure, PSmaximum pressure for which the protected equipment is designed3.4overpressurepressure increase over set pressure, usually expressed as a percentage of the set pressure3.5relieving pressurepres
48、sure used for the sizing of a safety valve which is greater than or equal to the set pressure plus overpressure3.6back pressurepressure that exists at the outlet of a safety valve as a result of the pressure in the discharge systemNote 1 to entry: The back pressure is the sum of the superimposed and
49、 built-up back pressures.3.7built-up back pressurepressure existing at the outlet of a safety valve caused by flow through the valve and the discharge system3.8superimposed back pressurepressure existing at the outlet of a safety valve at the time when the device is required to operateNote 1 to entry: It is the result
