BS ISO 27895-2009 真空技术.阀门.密封性试验.pdf

BS ISO 278952009 ICS 23.160 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BRITISH STANDARD Vacuum technology Valves Leak test Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 January 2010 BSI 2010 ISBN 978 0 580 61717 1 Amendments/corrigenda issued since publication DateComments BS ISO 278952009 National foreword This British Standard is the UK implementation of ISO 278952009. The UK participation in its preparation was entrusted to Technical Committee MCE/8/-/4, Vacuum technology. 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 for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 Reference number ISO 278952009E ISO 2009 INTERNATIONAL STANDARD ISO 27895 First edition 2009-12-15 Vacuum technology Valves Leak test Technique du vide Vannes vide Essai dtanchit des vannes vide Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer pering the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. 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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 Switzerland ii ISO 2009 – All rights reserved Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E ISO 2009 – All rights reserved iii Contents Page Foreword ............................................................................................................................................................iv Introduction.........................................................................................................................................................v 1 Scope......................................................................................................................................................1 2 Normative references............................................................................................................................1 3 Terms and definitions...........................................................................................................................1 4 Symbols..................................................................................................................................................4 5 Requirements.........................................................................................................................................5 6 Test s.........................................................................................................................................5 6.1 Valve seat leak test................................................................................................................................5 6.2 Valve body leak test..............................................................................................................................7 6.3 Leak test on minimum and maximum pressures of compressed air for pneumatic valve operation optional...............................................................................................................................9 6.4 Leak test on minimum and maximum torques of manual valve optional.....................................9 6.5 Leak test in operating temperature range optional.........................................................................9 6.6 Leak test after baking optional..........................................................................................................9 7 Test report..............................................................................................................................................9 Bibliography......................................................................................................................................................11 Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E iv ISO 2009 – All rights reserved Foreword ISO 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 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 International 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 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 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. ISO 27895 was prepared by Technical Committee ISO/TC 112, Vacuum technology. Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E ISO 2009 – All rights reserved v Introduction Vacuum valves are the most common parts in vacuum systems. Valve manufacturers provide technical data for vacuum valves based on their own test s and end users use these data to select valves. However, until the time of publication, there has been no International Standard specifying leak test s for vacuum valves even though leak rate data are among the most fundamental. For example, the leak rate of the valve may vary in the time interval between gas filling and leak testing. There are three different types of leak a real leaks, i.e. macroscopic cracks or holes allowing gases to pass through; b virtual leaks, caused by outgassing of volatile material inside a vacuum system or trapped volume; c permeation leaks, i.e. microscopic holes of diameter comparable to that of an atom, which occur throughout the construction material, e.g. in elastomers. Virtual leaks are not measurable by the leak test specified in this International Standard. Valve design and the materials used should therefore be chosen to minimize the risk of virtual leaks occurring. Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 INTERNATIONAL STANDARD ISO 278952009E ISO 2009 – All rights reserved 1 Vacuum technology Valves Leak test 1 Scope This International Standard specifies s for the leak testing of vacuum valves used for control of gas flow or vacuum pressure in a vacuum system. It is applicable to vacuum valves that can be closed to leak rates less than 1 10−5 Pa m3/s for trace gas. The s employ a sealing arrangement for the valve body, which is also specified in this International Standard. The s are suitable for the verification of valve specifications. A valve leak rate less than the nominal leak rate specified by the manufacturer during and after the operation enables the specification of such valve operating conditions as operating pressure range, permissible pressure difference between ports, bake-out temperature or operating temperature, and life cycle. NOTE 1 The data for large valves and valves without a valve body can vary from those obtained during delivery inspection depending on the accuracy of the attachment surface of the vacuum device. NOTE 2 The data obtained from this procedure is based on the testing conducted on an individual unit of a vacuum valve and they can be different from those obtained during delivery inspection if the test is pered with the valve incorporated into the equipment. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. ISO 3530, Vacuum technology Mass-spectrometer-type leak detector calibration 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 leak rate q 〈vacuum valve technology〉 throughput of a trace gas, which passes through a crack, hole or gap in the wall, seat or sealing material of a valve under specific conditions NOTE 1 Adapted from ISO 35301979, 2.5.1. NOTE 2 The leak rate is expressed in pascal cubic metres per second. NOTE 3 The leak rate of the trace gas can be measured using a mass spectrometer-type leak detector. The leak rate depends on type of gas, pressure difference, and temperature. NOTE 4 The definitions standard air leak rate 3.2 and equivalent standard air leak rate 3.3 are more specific. Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E 2 ISO 2009 – All rights reserved 3.2 standard air leak rate throughput, through an opening such as a crack or hole, of atmospheric air having a dew point of less than −25 C under standard conditions an inlet pressure of 100 5 kPa; an outlet pressure of less than 1 kPa; and a temperature of 23 7 C NOTE 1 Adapted from ISO 35301979, 2.5.2. NOTE 2 The standard conditions are taken from ISO 3530. 3.3 equivalent standard air leak rate short-path leaks of the molecular type having standard air leak rates of less than 10−7 Pa m3/s EXAMPLE Helium relative atomic mass 4 passes through such leaks more rapidly than air average relative molecular mass 29,0, and a given flow rate of helium corresponds to a smaller flow rate of air. NOTE 1 “Equivalent standard air leak rate” is taken as 4/291/2 0,37 times the helium leak rate under the standard conditions specified in ISO 3530. NOTE 2 Adapted from ISO 35301979, 2.5.3. 3.4 trace gas gas used to detect leaks NOTE Mass-spectrometer-type leak detectors are used as the leak measurement instrument. If a helium mixture is used, the leak rate is reported as a helium-equivalent value. 3.5 operating pressure po 〈vacuum valve technology〉 pressure range for a valve in working condition NOTE If a pressure is within the operating pressure range, the valve can have a leak rate smaller than that specified by the manufacturer. 3.6 maximum operating pressure po, max 〈vacuum valve technology〉 highest pressure at which the valve operates within its specifications 3.7 Pressure difference NOTE 1 Figures 1 and 2 show schematic diagrams of angle valves and gate valves, respectively. NOTE 2 Manufacturers of bellow-sealed angle valves often specify a maximum pressure difference separated as differential pressures in the opening and closing directions. Usually, the critical case is the differential pressure in the opening direction p1 at “vacuum” and p2 at maximum pressure. 3.7.1 pressure difference ∆p 〈conventional angle and gate valves〉 pressure difference between p1 and p2, where p2 is the pressure at the space toward the valve disc with elastomer on the valve seat and p1 is the pressure of the opposite side within the valve Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E ISO 2009 – All rights reserved 3 3.7.2 pressure difference ∆p 〈bellow-sealed angle valves〉 pressure difference between p1 and p2, where in the opening direction p1 is the residual pressure at “vacuum” and p2 is the maximum pressure Key 1 port A 2 port B Figure 1 Angle valve Key 1 port A 2 port B Figure 2 Gate valve 3.8 maximum pressure difference ∆pmax greatest pressure difference at which the valve can operate normally NOTE If a pressure difference is lower than ∆pmax, the valve can have a leak rate smaller than that specified by the manufacturer. 3.9 pressure range of compressed air for a pneumatic valve pp pressure range of the compressed air specified by the manufacturer for a pneumatic valve closed or opened by compressed air Licensed Copy athen reading, Reading University Library, 31/01/2010 0510, Uncontrolled Copy, c BSI BS ISO 278952009 ISO 278952009E 4 ISO 2009 – All rights reserved NOTE The compressed air pressure can be specified not only as an absolute pressure but also as a pressure relative to atmospheric, i.e. the gauge pressure. 3.10 torque range for valves with an operating torque specified τ torque range specified by the manufacturer for a valve operated by torque wrench 3.11 operating temperature To temperature at which the valve operates under normal conditions NOTE An operating temperatur