1、BSI Standards PublicationBS EN ISO 4126-4:2013Safety devices for protectionagainst excessive pressurePart 4: Pilot-operated safety valvesBS EN ISO 4126-4:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO4126-4:2013. It supersedes BS EN ISO 4126-4:2004 whi
2、ch iswithdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PSE/18/6, Industrial valves, steam traps, actuators andsafety devices against excessive pressure - Safety devices againstexcessive pressure.A list of organizations represented on this committee can beobtained
3、on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 66504 2ICS 13.240Compliance with a Britis
4、h Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2013.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 4126-4 July 2013
5、 ICS 13.240 Supersedes EN ISO 4126-4:2004English Version Safety devices for protection against excessive pressure - Part 4: Pilot-operated safety valves (ISO 4126-4:2013) Dispositifs de scurit pour protection contre les pressions excessives - Partie 4: Soupapes de sret pilotes (ISO 4126-4:2013) Sich
6、erheitseinrichtungen gegen unzulssigen berdruck - Teil 4: Pilotgesteuerte Sicherheitsventile (ISO 4126-4:2013)This European Standard was approved by CEN on 28 December 2012. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this Europ
7、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
8、 (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
9、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
10、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
11、ef. No. EN ISO 4126-4:2013: EBS EN ISO 4126-4:2013EN ISO 4126-4:2013 (E) 3 Foreword This document (EN ISO 4126-4:2013) has been prepared by Technical Committee ISO/TC 185 “Safety devices for protection against excessive pressure“ in collaboration with Technical Committee CEN/TC 69 “Industrial valves
12、” the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by 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. Atte
13、ntion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 4126-4:2004. This document has been prepared under a manda
14、te given to CEN by the European Commission and the European Free Trade Association, and supports essential requirements of EU Directive(s). For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN-CENELEC Internal Regulations,
15、the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lat
16、via, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 4126-4:2013 has been approved by CEN as EN ISO 4126-4:2013 without any modification. BS EN ISO 4126-4:2
17、013EN ISO 4126-4:2013 (E) 4 Annex ZA (informative) Relationship between this International Standard and the Essential Requirements of EU Directive 97/23/EC (PED) By agreement between ISO and CEN, this CEN annex is included in the DIS and the FDIS but will not appear in the published ISO standard. Th
18、is International Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association to provide one means of conforming to Essential Requirements of the New Approach Directive 97/23/EC (PED). Once this standard is cited in the Official Journal o
19、f the European Communities under that Directive and has been implemented as a national standard in at least one Member State, compliance with the normative clauses of this standard given in Table ZA.1 confers, within the limits of the scope of this standard, a presumption of conformity with the corr
20、esponding Essential Requirements of that Directive and associated EFTA regulations. Table ZA.1 Correspondence between this International Standard and Directive 97/23/EC (PED) Sub-clauses of this International Standard Essential Requirements of Directive 97/23/EC (PED) Essential Requirements Annex I
21、of PED 5,6,7,8,9 Safety accessories 2.11.1 5.1.5 Safety of operation 2.3 5.1.6 Drain and venting 2.5 6.3 Proof test 3.2.2 10 Marking and labelling 3.3 WARNING: Other requirements and other EU Directives may be applicable to the products falling within the scope of this standard. BS EN ISO 4126-4:201
22、3ISO 4126-4:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols and units . 55 Design 55.1 General . 55.2 Valve end connections 65.3 Minimum requirements for springs . 65.4 Materials . 76 Production testing 76.1 Purp
23、ose 76.2 General . 76.3 Hydrostatic testing 76.4 Pneumatic testing . 86.5 Adjustment of set or cold differential test pressure . 86.6 Seat leakage test. 96.7 Pressure seals 97 Type testing 97.1 General . 97.2 Tests to determine operating characteristics 107.3 Tests to determine flow characteristics
24、127.4 Determination of the coefficient of discharge .147.5 Certification of coefficient of discharge 148 Determination of pilot operated safety valve performance .149 Sizing of pilot operated safety valves .1410 Marking and sealing .1410.1 Marking 1410.2 Sealing of a pilot operated safety valve . 15
25、Bibliography .16BS EN ISO 4126-4:2013ISO 4126-4:2013(E)ForewordISO (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.
26、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, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Internat
27、ional 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 Standar
28、ds 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 o
29、f patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 4126-4 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 4126-4:2004), which has
30、 been technically revised. It also incorporates the Technical Corrigendum ISO 4126-4:2004/Cor 1:2007.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 v
31、alves and bursting disc safety devices in combination Part 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 devi
32、ces excluding stand-alone bursting disc safety devices Part 10: Sizing of safety valves for gas/liquid two-phase flow Part 11: Performance testing1)Part 7 contains data that is common to more than one of the parts of ISO 4126 to avoid unnecessary repetition.1) Under development.iv ISO 2013 All right
33、s reservedBS EN ISO 4126-4:2013INTERNATIONAL STANDARD ISO 4126-4:2013(E)Safety devices for protection against excessive pressure Part 4: Pilot operated safety valves1 ScopeThis part of ISO 4126 specifies general requirements for pilot operated safety valves, irrespective of the fluid for which they
34、are designed. In all cases, the operation is carried out by the fluid in the system to be protected.It is applicable to pilot operated safety valves having a valve flow diameter of 4 mm and above which are for use at set pressures of 0,1 bar gauge and above. No limitation is placed on temperature.Th
35、is is a product standard and it is not applicable to applications of pilot operated safety valves.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest
36、edition of the referenced document (including any amendments) applies.ISO 4126-7:2013, Safety devices for protection against excessive pressure Part 7: Common data3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1pilot operated safety valveself-ac
37、tuated device comprising a main valve and an attached pilotNote 1 to entry: The pilot responds to the pressure of the fluid without any other actuating energy than the fluid itself and controls the operation of the main valve. The main valve opens when the fluid pressure that keeps it closed is remo
38、ved or reduced. The main valve re-closes when the pressure is re-applied.Note 2 to entry: See Figure 1 for a list of main components.3.2main valveparts of a pilot operated safety valve, through which the discharge capacity is achieved3.3flowing pilotpilot which discharges the fluid throughout the re
39、lieving cycle of the pilot operated safety valve ISO 2013 All rights reserved 1BS EN ISO 4126-4:2013ISO 4126-4:2013(E)Key1 equipment to be protected 9 disc (or piston)2 main valve 10 seat3 pilot valve 11 main valve body4 sensing line 12 main valve inlet5 loading/unloading line 13 main valve outlet6
40、pressure chamber 14 pilot outlet7 cover (or cap) 15 connection of the sensing line (see Note)8 guideNOTE The sensing line from the pilot can be either connected to the main valve inlet or connected directly to the equipment to be protected. In cases where the sensing line is not connected to the mai
41、n valve inlet, considerations should be given to the length and to the protection from damage of the sensing line.Figure 1 Nomenclature of main components of a pilot operated safety valve3.4non-flowing pilotpilot in which the fluid flows only during the opening and/or closing of the pilot operated s
42、afety valve3.5ON/OFFaction characterized by stable operation resulting in fully open or fully closed main valve positionNote 1 to entry: This is an action of the pilot operated safety valve.2 ISO 2013 All rights reservedBS EN ISO 4126-4:2013ISO 4126-4:2013(E)3.6modulatingaction characterized by a gr
43、adual opening and closing of the disc of the main valve which is a function of the pressure, proportional but not necessarily linearNote 1 to entry: This is an action of the pilot operated safety valve.3.7set pressurepredetermined pressure at which the main valve of a pilot operated safety valve und
44、er operating conditions commences to openNote 1 to entry: It is the gauge pressure measured at the main valve inlet at which the pressure forces tending to lift the main valve disc for the specific service conditions are in equilibrium with the forces retaining the main valve disc on its seat.3.8max
45、imum allowable pressurePSmaximum pressure for which the protected equipment is designed3.9opening sensing pressurepressure at which the pilot commences to open in order to achieve the set pressure3.10overpressurepressure increase over the set pressure, usually expressed as a percentage of the set pr
46、essure3.11reseating pressurevalue of the inlet static pressure at which the main valve disc re-establishes contact with the seat or at which the lift becomes zero3.12cold differential test pressureinlet static pressure at which a pilot operated safety valve is set to commence to open on the test ben
47、chNote 1 to entry: This test pressure includes corrections for service conditions, e.g. back pressure and/or temperature.3.13relieving pressurepressure used for the sizing of a pilot operated safety valve which is greater than or equal to the set pressure plus overpressure3.14back pressurepressure t
48、hat 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 built-up back pressures.3.15built-up back pressurepressure existing at the outlet of the main valve caused by flow through the main valv
49、e and the discharge system3.16superimposed back pressurepressure existing at the outlet of the main valve at the time when the device is required to operateNote 1 to entry: It is the result of pressure in the discharge system from other sources. ISO 2013 All rights reserved 3BS EN ISO 4126-4:2013ISO 4126-4:2013(E)3.17blowdowndifference between set and reseating pressuresNote 1 to entry: Blowdown is normally stated as a percentage of set pressure except for pressures of less than 3 bar when the blowdown is expressed in bar.3.18liftactual trave
