【正文】 standard only when incorporated in it by amendment or revision. For undated references the latest edition of the reference applies. EN 473 Qualification and certification of NDT personnel General principles EN 13308 Nondestructive testing Terminology Part 8: Terms used in leak tightness testing 3 Definitions For the purposes of this standard, the definitions given in EN 13308 apply. 4 Personnel qualification It is assumed that leak testing is performed by qualified and capable personnel. In order to prove this qualification, it is remended to certify the personnel in accordance with EN 473. 5 Units The leakage rate is defined as the pVthroughput of a specific fluid which passes through a leak under specific conditions and is expressed in Pascals cubic metre per second. In the past, the leakage rate was expressed in various units, these are given in informative Annex B. 6 Tightness requirements The leak tightness of an object is usually determined by measurement of its gas leakage rate. Leak tightness is monly described as the flow rate of fluid into or from the test object. For a gas, leak tightness may be conveniently indicated by the variation of pressure with time under specified conditions. For testing, however, . when drafting specifications and procedures, the leak tightness shall be expressed as leakage rate in units of gas throughput (Pa?m3/s) for a specific gas at specified temperature and at specified pressure conditions. Zero leakage rate shall not be specified. The required leak tightness shall be related to the function of the object under consideration. Page 5 EN 1779:1999 NOTE 1: Examples of relationship between leakage rate and the object: leakage rates in the order of 5 x 10 4 Pa?m3/s can be acceptable for pressed air cylinders (this corresponds to a pressure variation of 5000 Pa in a 10 l volume in 24 hours or 0,5 l loss measured at atmospheric pressure)。 Europ233。fung Kriterien zur Auswahl eines Pr252。res de choix de la m233。233。 BSI 10 February 2022 ISBN 0 580 32931 3 Summary of pages This document prises a front cover, an inside front cover, the EN title page, pages 2 to 18, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication EUROPEAN STANDARD EN 1779 August 1999 NORME EUROP201。BRITISH STANDARD BS EN 1779:1999 Incorporating Amendment No. 1 Nondestructive testing — Leak testing — Criteria for method and technique selection The European Standard EN 1779:1999, with the incorporation of amendment A1:2022, has the status of a British Standard ICS Amd. No. Date Comments 14968 10 February 2022 Revision to Foreword page and deletion of Annex ZA BS EN 1779:1999 National foreword This British Standard is the English language version of EN 1779:1999, including amendment A1:2022. The UK participation in its preparation was entrusted to Technical Committee WEE/46, Nondestructive testing, which has the responsibility to: — aid enquirers to understand the text。ENNE + A1 December 2022 EUROP196。tanch233。thode et de la technique (inclut l’amendement A1:2022) Zerst246。fverfahrens (enth228。en de Normalisation Europ228。 a leakage rate of 1010 Pa?m3/s is typical for cardiac pacemakers (this corresponds to a loss of 1 cm3 every 30 years approximately). The total tightness of a system can be considered in terms of tightness for all ponents of that system. To meet requirements the sum of the leakage rates for each ponent plus the sum of the leakage rates at each connecting point shall be less than the overall allowable leakage rate of the system. The tightness of ponent or system shall be specified under normal operating conditions. NOTE 2 : The following factors have the most significant influence on tightness: the nature and pressure of the gas。 4) choose the appropriate method (A to D, from the normative Annex A)。 and T 2 T 1 are the leakage rates in Pa?m3/s associated with T and T1。 50%. 8 General principles of method and technique selection In the selection of a test technique (see normative Annex A) the following points shall be considered: a) range of allowable leakage rates (see )。 tests during manufacture or inservice test (see )。 3) helium or hydrogen may present problems with some elastomers/polymers since permeation can be significant. NOTE 3: Surface finish can also restrict the applicability of some techniques or influence their results. Examples are evacuation difficulties, inadequate leak tightness for seals in vacuum box applications, false indications (bubble test), etc. Operation and testing conditions Generally a test fluid other than the operating fluid is used in order to increase test sensitivity or to reduce hazard or pollution. The difference between the properties of the fluids shall be taken into account to avoid wrong results due to physical or chemical phenomena (see material patibility) and to evaluate, if necessary, the true leakage under operating conditions. Page 11 EN 1779:1999 Whenever possible the test shall be performed with the leakage flow in the same direction and with the pressure in the same range as under the operating conditions. If it is not possible, deviations from the operating conditions shall be stated in the test report. NOTE 1: Leaks can show a very different behaviour for reverse flow, particularly if