【正文】 cability Remarks Vacuum technique (total) Usually helium The object is evacuated and connected to the detector。 NOTE 2: certain tracer gases are not patible with some materials and problems due to corrosion, sorption or permeation may occur. For example: 1) halogen gases (except SF6) are not usable for the testing of nickel alloys and stainless steels。 tests during manufacture or inservice test (see )。 c) item design, . dimensions, openings and surface accessibility, pressure and vacuum design limits, materials (walls, gaskets,..), surface finish (see )。 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 )。 G 2 G 1 1 2 M G1 and M G 2 are the molar masses, in kilograms per mole of the gases G1 and G2。 and T 2 T 1 are the leakage rates in Pa?m3/s associated with T and T1。 and B1 B2 are different upstream pressures in Pascals。 4) choose the appropriate method (A to D, from the normative Annex A)。 2) define the extent of the investigation: total or local area。 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。r Normung Central Secretariat: rue de Stassart 36, B1050 Brussels 169。en de Normalisation Europ228。nderung A1:2022) This European Standard was approved by CEN on 10 July 1999, and amendment A1 was approved by CEN on 20 November 2022. CEN members are bound to ply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Uptodate 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, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit233。fverfahrens (enth228。fung – Dichtheitspr252。thode et de la technique (inclut l’amendement A1:2022) Zerst246。 Crit232。tanch233。les d39。ENNE + A1 December 2022 EUROP196。 — monitor related international and European developments and promulgate them in the UK. A list of anizations represented on this mittee can be obtained on request to its secretary. Crossreferences The British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled ―International Standards Correspondence Index‖, or by using the ―Search‖ facility of the BSI Electronic Catalogue or of British Standards Online. 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 does not of itself confer immunity from legal obligations. This British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and es into effect on 15 November 1999 169。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。 — present to the responsible European mittee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed。 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 E