【正文】 ng 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。 2) define the extent of the investigation: total or local area。 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。 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。 the points to be checked are covered by paint or a strip which chemically reacts with ammonia and changes colour Vacuum pump unit, ammonia sensitive paint or strip Equipment for safe handling and disposal of ammonia Apparatus for post cleaning and inspection Test object material shall be patible with ammonia 107 Pa?m3/s Location Preevacuation may be unnecessary if a loss of sensitivity is tolerated Presence of moisture can significantly reduce the test sensitivity Risk of explosion in mixture with air Ammonia is toxic and requires care in the handling and disposal Vacuum box, using internal pressure of tracer gas Tracer gas (usually helium) The ponent is filled with tracer gas。 tests during manufacture or inservice test (see )。 and T 2 T 1 are the leakage rates in Pa?m3/s associated with T and T1。 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。fverfahrens (enth228。tanch233。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。233。fung Kriterien zur Auswahl eines Pr252。 1999 All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1779:1999 + A1:2022 E Page 2 EN 1779:1999 Contents Page Foreword 3 1 Scope 4 2 Normative references 4 3 Definitions 4 4 Personnel qualification 4 5 Units 4 6 Tightness requirements 4 7 Leak testing 5 8 General principles of method and technique selection 9 Annex A (normative) Specific features of leak testing methods 12 Annex B (informative) Conversion factors for leakage rate units 18 Page 3 EN 1779:1999 Foreword This European Standard has been prepared by Technical Committee CEN/TC 138 Nondestructive testing, 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 February 2022, and conflicting national standards shall be withdrawn at the latest by February 2022. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards anizations 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. Foreword to amendment A1 This document EN 1779:1999/A1:2022 has been prepared by Technical Committee CEN/TC 138 “Nondestructive testing”, the secretariat of which is held by AFNOR. This Amendment to the European Standard EN 1779:1999 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2022, and conflicting national standards shall be withdrawn at the latest by June 2022. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Asso