www bzfxw com Copyright British Standard Reproduced by IHS under ` , , , , ` ` , ` , , , , ` , , , ` , , ` , ` , ` ` , , ` ` , , ` , , ` , ` , , ` BRITISH STANDARD BS EN 849 1997 Incorporating Amendme[.]
BS EN 849:1997 BRITISH STANDARD Incorporating Amendments Nos and Transportable gas cylinders — Cylinder valves — Specification and type testing `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - The European Standard EN 849:1996, with the incorporation of amendments A1:1999 and A2:2001, has the status of a British Standard ICS 23.060.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 BS EN 849:1997 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PVE/3, Gas containers, upon which the following bodies were represented: Aluminium Extruders’ Association Aluminium Federation British Compressed Gases Association British Fire Consortium British Gas plc British Iron and Steel Producers’ Association British Soft Drinks Association Ltd Engineering Equipment and Materials Users’ Association Fire Extinguishing Trades Association Health and Safety Executive Home Office Institution of Chemical Engineers LP Gas Association Marine Safety Agency Ministry of Defence National Engineering Laboratory National Physical Laboratory Safety Assessment Federation Ltd Safety Equipment Association Tubes Investments Limited The following bodies were also represented in the drafting of the standard, through sub-committees and panels: British Association of Breathing Apparatus Service Engineers This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 March 1997 Department of Health © BSI 14 January 2002 Amendments issued since publication The following BSI references relate to the work on this standard: Committee reference PVE/3 Draft for comment 92/812941 X Amd No Date Comments 10588 November 1999 Addition of new Annex C 13345 14 January 2002 Indicated by a sideline ISBN 580 26783 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Tube Investments Chesterfield Tube Co Ltd BS EN 849:1997 Contents Committees responsible National foreword Page Inside front cover ii Foreword Text of EN 849 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - © BSI 14 January 2002 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 i BS EN 849:1997 National foreword This British Standard has been prepared by Technical Committee PVE/3 and is the English language version of EN 849:1996 Transportable gas cylinders — Cylinder valves — Specification and type testing, including amendments A1:1999 and A2:2001, published by the European Committee for Standardization (CEN) EN 849 was produced as a result of international discussions in which the United Kingdom took an active part This British Standard partially supersedes BS 341-1:1962, BS 341-1:1991 and BS 341-2:1963 which will be amended to elimate conflicting requirements `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue The Technical Committee has reviewed the provisions of ISO 5145:1990 to which normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard A British Standard does not purport to include all the necessary provisions of a contract Users of British Standards are responsible for their correct application Compliance with a British Standard does not of itself confer immunity from legal obligations Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages to 24, an inside back cover and a back cover The BSI copyright notice displayed in this document indicates when the document was last issued Sidelining in this document indicates the most recent changes by amendment ii Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - EUROPEAN STANDARD EN 849 NORME EUROPÉENNE July 1996 + A1 EUROPÄISCHE NORM April 1999 + A2 June 2001 ICS 23.060.00 Descriptors: Gas cylinders, compressed gases, liquified gases, dissolved gases, gas valves, design, performance evaluation, conformity tests, marking English version Transportable gas cylinders — Cylinder valves — Specification and type testing (includes amendments A1:1999 and A2:2001) Bouteilles gaz transportables — Robinets de bouteilles — Spécifications et essais de type (inclut les amendements A1:1999 et A2:2001) Ortsbewegliche Gasflaschen — Flaschen-Ventile — Spezifikation und Typprüfung (enhält Änderungen A1:1999 und A2:2001) ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ This European Standard was approved by CEN on 1996-01-22; amendment A1 was approved by CEN on 1999-01-08 Amendment A2:2001 was approved by CEN on 2001-05-10 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European 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 Central Secretariat or to any CEN member This European Standard exists in three official versions (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 Central Secretariat has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1996 Copyright reserved to CEN members Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Ref No EN 849:1996 + A1:1999 + A2:2001 E Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 EN 849:1996 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Foreword This European Standard has been prepared by Technical Committee CEN/TC 23, Transportable gas cylinders, the Secretariat of which is held by BSI 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 1997, and conflicting national standards shall be withdrawn at the latest by January 1997 This European Standard has been submitted for reference into the RID and/or the technical annexes of the ADR Therefore in this context the standards listed in the normative references and covering basic requirements of the RID/ADR not addressed within the present standard are normative only when the standards themselves are referred to in the RID and/or the technical annexes of the ADR According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom Foreword to amendment A1 This amendment EN 849:1996/A1:1999 to EN 849:1996 has been prepared by Technical Committee CEN/TC 23, Transportable gas cylinders, the Secretariat of which is held by BSI This amendment to the European Standard EN 849:1996 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October 1999, and conflicting national standards shall be withdrawn at the latest by October 1999 This European Standard has been submitted for reference into the RID and/or the technical annexes of the ADR Therefore in this context the standards listed in the normative references and covering basic requirements of the RID/ADR not addressed within the present standard are normative only when the standards themselves are referred to in the RID and/or the technical annexes of the ADR Foreword to amendment A2 This amendment EN 849:1996/A2:2001 to EN 849:1996 has been prepared by Technical Committee CEN/TC 23, Transportable gas cylinders, the Secretariat of which is held by BSI This amendment to the European Standard EN 849:1996 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2001, and conflicting national standards shall be withdrawn at the latest by December 2001 This amendment to EN 849 has been prepared to align certain requirements with RID/ADR This European Standard has been submitted for reference into the RID and/or the technical annexes of the ADR Therefore in this context the standards listed in the normative references and covering basic requirements of the RID/ADR not addressed within the present standard are normative only when the standards themselves are referred to in the RID and/or the technical annexes of the ADR ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom This amendment to EN 849 has been prepared to clarify certain important parameters and aspects of testing cyclinder valves in accordance with EN 849, 5.4.4 According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 EN 849:1996 Contents Page Foreword Introduction Scope Normative references Definitions and symbols 4 Valve requirements 5 Prototype valve test Marking 18 Test report 18 Annex A (normative) Valve impact test 19 Annex B (informative) Example of test sequence 21 Annex C (normative) Endurance test 22 Figure — External tightness Figure — Internal tightness Figure — Maximum dimensions for gas cylinder valves, protected by a cap Figure — Example of an ignition test installation 15 Figure — Pressure cycle specification 16 Figure — Example of acetylene flashback test apparatus 17 Figure A.1 — Impact test 20 Figure C.1 — Typical arrangement of computer controlled equipment 23 Figure C.2 — Diagram showing a typical cycle for endurance test 24 Table — Sequence of tests (tightness, endurance and fire resistance) for type approval (no variants) 11 Table — Test pressures for tightness tests 12 Table — Test sequence 14 Deleted Table B.1 — Sequence of tests for type approval (basic design plus two type variants) 21 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - © BSI 14 January 2002 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 EN 849:1996 Introduction The increased use of compressed gases has led to a corresponding increase in the number of gas cylinders that are in circulation throughout the world Each gas cylinder is fitted with a valve, to contain and control the discharge of its contents Such valves normally conform to standards of performance and safety Scope This European Standard specifies requirements for gas cylinder valves and the method of testing such valves, for type approval This standard is applicable to valves to be fitted to gas cylinders, up to 150 l water capacity, intended to convey compressed, liquefied or dissolved gases This standard is only applicable to valves operated by a hand wheel or a key This standard is not applicable to valves for breathing equipment, fire extinguishers or cryogenic equipment This standard is primarily for industrial gases other than LPG but may also be applied for LPG However for dedicated LPG cylinders, see prEN 13153:1998, Specification and testing for Liquefied Petroleum Gases (LPG) — Cylinder valves — Manually operated, prepared by CEN/TC 286, Liquefied petroleum gas equipment and accessories Normative references This European Standard incorporates by dated or undated reference, provisions from other publications These normative references are cited at the appropriate place in the text and the publications are listed hereafter For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision For undated references the latest edition of the publication referred to applies EN 720-2, Transportable gas cylinders — Gases and gas mixtures — Part 2: Determination of flammability and oxidizing ability of gases and gas mixtures EN 962, Transportable gas cylinders — Valve protection caps and valve guards for industrial and medical gas cylinders — Design, construction and tests ISO 188, Rubber, vulcanized — Accelerated ageing or heat-resistance tests ISO 1817, Rubber, vulcanized — Determination of the effect of liquids ISO 5145:1990, Cylinder valve outlets for gases and gas mixtures — Selection and dimensioning Definitions and symbols For the purposes of this standard, the following definitions and symbols apply 3.1 working pressure (pw) settled pressure, at a uniform temperature of 15 ºC, for a full gas cylinder 3.2 operating pressure (po) varying pressure which is developed in a cylinder during service 3.3 valve test pressure (pvt) for compressed gases: pvt = 1,2 × pw for liquefied gases and dissolved gases under pressure (for example, acetylene): pvt shall be at least equal to the minimum test pressure of the cylinder quoted in the relevant transport regulation for that gas or gas group Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ EN 629-1, Transportable gas cylinders — 25E taper thread for connection of valves to gas cylinders — Part 1: Specification EN 849:1996 3.4 external tightness tightness to atmosphere (leakage in and/or leakage out) when the valve is open (see Figure 1) 3.5 internal tightness tightness across the valve seat (leakage in and/or leakage out) when the valve is closed (see Figure 2) 3.6 minimum closing torque (Tc) minimum closing torque necessary to obtain the internal tightness 3.7 resistance torque maximum closing torque the valve can withstand without damage 3.8 valve operating mechanism manually rotated device, which closes and opens the valve orifice Valve requirements 4.1 General Valves shall operate satisfactorily over the full range of service temperatures, normally from – 20 ºC to +65 ºC The range may be extended for short periods (e.g during filling) Where higher or lower service temperatures are required for longer periods, the purchaser shall specify accordingly ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ Valves shall be capable of withstanding the mechanical stresses or chemical attack they may experience during normal service Valves shall be cleaned to meet the requirements of the intended service 4.2 Description and dimensions A cylinder valve comprises: — a body; — a valve operating mechanism and internal sealing device; — an external sealing mechanism; — a connection(s) for usage (fill and discharge); — a connection system, between the valve and gas cylinder; and occasionally: — a safety device, against overpressurization; — a siphon tube; — a screwed plug or cap, on the outlet connection, to ensure leak tightness or protection; — an excess flow limiting device The bore of the valve shall be adequate to meet the requirements of flow rate, without unacceptably reducing the strength of the stem connection The bore diameter, typically 3,5 mm for valves with a 25E stem thread (see EN 629-1) and mm for valves with a 17E stem thread, shall be agreed between customer and supplier Where a valve is to be protected by a cap in accordance with EN 962 the valve should comply with the dimensions given in Figure `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - © BSI 14 January 2002 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 EN 849:1996 4.3 Materials Metallic and non-metallic materials in contact with the gas shall be chemically and/or physically compatible with the gas, under all intended operating conditions Compatibility of materials with oxygen and other oxidizing gases, ignition resistance of materials and lubricants, shall be established by an appropriate test procedure Valves for acetylene may be manufactured from copper based alloys if the copper content does not exceed 70 % (by weight) The manufacturer shall not use any procedure resulting in copper enrichment of the surface Silver content of alloys shall be limited for acetylene valves The acceptable limit varies between 43 % (by weight) and 50 % (by weight), depending on the composition of the alloy Non-metallic sealing material for use with air, oxygen and oxygen enriched gases, shall be capable of withstanding an ageing sensitivity test in accordance with ISO 188 Non-metallic sealing material in valves shall be capable of withstanding corrosive media tests in accordance with ISO 1817 ｗｗｗ．ｂｚｆｘｗ．ｃｏｍ `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Figure — External tightness © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 EN 849:1996 5.4.3 Tightness tests 5.4.3.1 General Each internal and external tightness test sequence shall comprise a test at four pressure settings as shown in Table The test pressure shall be held for not less than minute Table — Test pressures for tightness tests Test pressure sequence Test pressure for tightness tests vacuum (e.g × 10–3 bar) if required 0,1 bar for toxic and flammable gases, 0,5 bar for all other gases 10 bar for all gases The higher of either pvt for permanent gases or the test pressure of the gas cylinder for liquefied and dissolved gases, but never less than 20 bar 5.4.3.2 Internal tightness The internal tightness shall be determined in relation to the closing torque in accordance with the following procedure, on each of the five or more sample valves (see 5.3): a) blank off the valve outlet connection; b) remove the safety relief device (where fitted) and seal the opening; c) open the valve; d) apply the specified pressure to the valve inlet; e) close the valve to the desired torque It is especially important that diaphragm valves are pressurized when the valve is being closed; f) open the valve outlet connection; g) wait at least before measuring the seat leakage rate; h) If the leakage rate is unacceptable (see 4.4.5) repeat the test sequence at a higher valve closing torque This test sequence shall be repeated for each test pressure given in Table 5.4.3.3 External tightness The external tightness shall be determined, using the following procedure, on each of the five or more sample valves (see 5.3): a) blank off one opening (inlet or outlet) of the valve; b) remove the safety relief device (where fitted) and seal the opening; c) fully open the valve; d) apply the specified pressure through the other opening; e) measure the leakage rate; f) partially close the valve; g) measure the leakage rate If required, action f) and action g) may be repeated for different partial closings For test sequence of Table 1, carried out at (–20 ± 2,5) °C, the external leakage rate shall also be measured while the handwheel is being rotated 12 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 EN 849:1996 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - 5.4.4 Endurance test An endurance test of 000 cycles, consisting of fully opening and closing of the valve, shall be carried out at pvt After each closure the pressure downstream of the seat shall be released to atmosphere There shall be, at least, a s pause at each fully open and fully closed position Care should be taken to ensure that, during the test, friction does not cause the valve temperature to exceed significantly that specified in Table For handwheel valves, the closing torque used during the test shall be N·m No significant torque shall be applied in the fully open position For key operated or diaphragm valves which require a minimum closing torque (Tc) greater than N·m, the torque used during the test shall be equal to 1,5 × Tc For small valves, with a minimum closing torque of less than N·m, the torque used, during the test, shall be twice the minimum closing torque, subject to a maximum of N·m For all subsequent tests, the torque used during the endurance test shall not be exceeded For further details see Annex C 5.4.5 Visual examination When the endurance test and the subsequent tightness tests have been completed, sealing elements such as diaphragms, bellows, O-rings, shall be subject to a visual check for unacceptable wear and/or damage 5.4.6 Determination of resistance to excessive torque The intent of these tests is to check that the valve operating mechanism has adequate strength, and fails safely if subjected to excessive torque These tests shall be carried out on the sample valves and 9, at atmospheric pressure The closing torque on sample valve shall gradually be increased to a given torque T (see below), at this torque the valve shall be able to work without noticeable difficulties and shall not show any significant damage The torque shall then be increased until failure occurs of any part of the operating device The value of the torque, at failure, shall be not less than 1,25 × T This test shall then be repeated, on sample valve 9, but with an opening torque instead of a closing torque After this test, the valve operating mechanism may be severely damaged and not working No pressure retaining components shall have failed Disassembly of the mechanism is not permitted during this test The value of T for standard industrial gas cylinder valves, fitted with a 65 mm diameter handwheel, is 20 N·m This value of T will vary with the design of valve and operating mechanism, it may, for small valves be lower and for key operated valves be greater The operating mechanism shall not be capable of withstanding a torque in excess of that required to disassemble the operating mechanism from the valve body (see 4.4.3) 5.4.7 Mechanical impact test If it is not intended for the valve to be protected during transport by a cap or another form of guarding, an impact test shall be carried out on valve sample 7, as described in Annex A 5.4.8 Oxygen pressure surge test This test shall be carried out for valves used in all applications where the gas or gas mixture is highly oxidizing (see EN 720-2) For all types of valve the pressure surge test shall be carried out with pure oxygen The purpose of the test is to check whether the valve withstands an oxygen pressure surge safely Three sample valves, samples 10 to 12, in the “as received” condition, or lubricated, if a lubricant is used for such a valve, shall be tested Before the test, the ignition test installation shall be checked for the required pressure rise (for examples of test installation and pressure cycle specification, see Figure and Figure 5) For this purpose the test valve, at the end of the m length of copper tube, is replaced by a reliable pressure gauge © BSI 14 January 2002 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 13 EN 849:1996 The maximum pressure at the dead end of the copper tube (measured by pressure gauge and recorded on an oscilloscope) shall be achieved within (20 ± 5) ms (time necessary to reach pvt starting from atmospheric pressure) Stabilization time at pvt is not fixed but shall be greater than or equal to s Before the next pressure surge the system (sample valve and copper tube) shall be depressurized down to atmospheric pressure Stabilization time at atmospheric pressure is not fixed but shall be greater than, or equal to s The total time of the pressure cycle shall be 30 s, as illustrated in Figure 5, total time is the time between the beginning of two consecutive pressure surges For calibration purposes, heated oxygen at (60 ± 3) ºC shall be used The quality of oxygen shall be: — minimum purity 99,5 %, by volume; — hydrocarbon content K 10 × 10–6 p.p.m Each test shall be carried out as follows: — supply oxygen at a temperature of (60 ± 3) ºC, directly into the connection of the valve to be tested, by means of a copper tube having an internal diameter of mm and a length of m The specified material and dimensions of the tube, are essential in order to ensure that a well defined energy input into the valve to be tested is achieved; — two test sequences shall be carried out in accordance with Table 3; — oxygen is heated up to (60 ± 3) ºC, in the oxygen pre-heater Inlet of oxygen, to the test sample valve, is controlled by a quick opening valve (see Figure 4) The test consists of subjecting the sample valve to 50 pressure cycles from atmospheric pressure to the valve test pressure (pvt) (see Figure 5) After the tests, the sample valve shall be dismantled and carefully checked, including close examination of non-metallic components It shall not show any traces of ignition Table — Test sequence Test sequence Valve operating system Valve stem Closed Open Open Sealed with a screwed metallic plug `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - 14 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002 EN 849:1996 `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - Figure — Example of an ignition test installation © BSI 14 January 2002 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy Document provided by IHS Licensee=Bureau Veritas/5959906001, 11/08/2004 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 15 EN 849:1996 Figure — Pressure cycle specification 5.4.9 Acetylene flashback test This test is for valves intended for acetylene service The purpose of the test is to establish whether the sample valve is able to withstand an acetylene flashback After the flashback test, it shall be possible to close the valve Where the sample valve is fitted with an integral pressure relief device, this device shall be closed for the test The acetylene cylinder used for the test, shall have a free volume at the top of the cylinder of approximately 150 cm3 The sample valve shall be screwed into an acetylene cylinder of l water capacity (prepared with porous mass and solvent) No neck filter shall be fitted to the cylinder or the valve The cylinder shall be filled with at least half of its maximum permissible quantity of acetylene An igniter tube of volume 30 cm3 is connected to the outlet boss (see Figure 6) This igniter tube is closed at one end by a bursting disc having a maximum burst pressure of 40 bar The decomposition of the acetylene, propagates into the cylinder causing, due to a pressure rise, the rupture of the bursting disc, hot decomposition gases flow out of the valve After 30 s the sample valve shall be closed, from a safe distance (i.e by remote operation) The cylinder shall be left until stable (approximately 24 h) The internal tightness of the valve shall then be checked, and the leakage rate shall not exceed 50 cm3/h `,,,,``,`,,,,`,,,`,,`,`,``,,-`-`,,`,,`,`,,` - 16 Copyright British Standards Institution Reproduced by IHS under license with BSI - Uncontrolled Copy © BSI11/08/2004 14 January Document provided by IHS Licensee=Bureau Veritas/5959906001, 06:09:50 MST Questions or comments about this message: please call the Document Policy Group at 303-397-2295 2002