3530 International Standard (ISO INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXKAYHAPOAHAR OPTAHW3ALMA TIO CTAHAAPTM3AUWMORGANISATION INTERNATIONALE DE NORMALISATION Vacuum technology -- Mass-spectrometer-type leak- detector calibration Technique du vide - Etalonnage des spectrometres de masse detecteurs de fuites First edition-1979-09-01 3530-1979 (E) UDC 621.52 : 620.165.29 : 543.51 Ref.ISO3530-1979 (E) Descriptors : vacuum technology, leak detectors, mass spectrometers, calibration. riaht International praanization for Standardization Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (ISO member bodies). The work of developing Interna- tional Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to governmentai, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as Internationai Standards by the ISo Council. International Standard ISO3530 was developed by Technical Committee ISO/TC 112, Vacuum technology, and was circulated to the member bodies in December 1978. It has been approved by the member bodies of the following countries : Australia Italy South Africa, Rep. of Belgium Japan Spain Chile Korea, Rep. of United Kingdom Czechoslovakia Mexico USA France Netherlands USSR Germany, F.R. Poland India Romania No member body expressed disapproval of the document. ? International Organization for Standardization,1979 Printed in Switzerland nforStandardization INTERNATIONALSTANDARD ISO 3530-1979 (E) Vacuum technology - Mass-spectrometer-type leak- detector calibration 0 Introduction Scope and field of application This InternationalStandard specifiesprocedurestobe usedfor This International Standard specifies procedures to be used for calibrating leak detectors of the mass-spectrometer type; that the calibration of mass-spectrometer-type leak detectors. is, for determining a sensitivity figure for such leak detectors. The procedures require the use of a calibrated leak anda stan- It dealsonlywithleak detectors whichhave anintegral high dard gas mixture; the preparation and standardization of these vacuum system to maintain the sensing element (mass spec- are outsidethescopeofthisInternational Standard.Hereafter, trometer tube) at a low pressure. Specifically excepted from thedesignation"leak detectorwill beusedto refertoa detec- treatment.are sensing elements without such a vacuum system. tor of the mass-spectrometer type. It is also to be understood that the procedures are not intended toconstituteacompleteacceptancetest;suchtestswillbethe A leak detector permits detection of leakage due tomechanical subject of a future International Standard. openings, such as pinholes, and of leakage due to permeation, such as. occurs through many polymeric materials. Virtual This International Standard concerns the use of helium-4. leaks, such as those due to surface desorption, vaporization, Nevertheless, the procedures described may be used for other and gas pockets, cannot, in general, be detected by a leak search gases such as argon-40, subject to appropriate precau- detector. tions. The range of leakage-rate calibration is limited to a specified The application of this International Standard is restricted to level since factors that are unimportant for larger leaks may leak detectors not capable of detecting leaks smaller than become significant for leak rates that are substantially smaller 10-12 Pa-m3.s-1. than 10-12 Pa-m3.s~1. Twoproceduresareoutlined,onefordeterminingtheminimum Objects being tested by a leak detector may be under high detectable leak rate and the other for determining the minimum vacuum, or, af the other extreme, under pressure greater than detectable concentration ratio. These are applicable to the