1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 1518:1998 The Europ
2、ean Standard EN 1518:1998 has the status of a British Standard ICS 19.100 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Non-destructive testing Leak testing Characterization of mass spectrometer leak detectorsThis British Standard, having been prepared under the direction of
3、 the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 August 1998 BSI 1998 ISBN 0 580 30042 0 BS EN 1518:1998 Amendments issued since publication Amd. No. Date Text affected National foreword This British Standard is the English language
4、version of EN 1518:1998. It supersedes BS 5914:1980 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee WEE/46, Non-destructive testing, which has the responsibility to: aid enquirers to understand the text; present to the responsible European committee a
5、ny enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references
6、The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue.
7、A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises
8、a front cover, an inside front cover, the EN title page, pages 2 to 12, an inside back cover and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights o
9、f exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1518:1998 E EUROPEAN STANDARD EN 1518 NORME EUROPE ENNE EUROPA ISCHE NORM April 1998 ICS 19.100 Descriptors: Non-destructive tests, gas permeability tests, leak detection, leak detectors, mass spectr
10、ometry, characteristics, instrument sensitivity English version Non-destructive testing Leak testing Characterization of mass spectrometer leak detectors Essais non destructifs Contro les de tanche ite Caracte risation des de tecteurs de fuite a spectrome trie de masse Zersto rungsfreie Pru fung Dic
11、htheitspru fung Charakterisierung von massenspektrometrischen Leckdetektoren This European Standard was approved by CEN on 25 March 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a nationa
12、l standard without any alteration. Up-to-date 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 o
13、ther 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,
14、 Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 1518:1998 BSI 1998 Foreword This European Standard has been prepared by Technical Committee CEN/TC 138, Non-destructive testing, the secretariat of which is held by AF
15、NOR. 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 October 1998, and conflicting national standards shall be withdrawn at the latest by October 1998. According to the CEN/CENELEC Internal Regula
16、tions, the national standards organizations 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 Un
17、ited Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Description of an MSLD 4 5 Apparatus for methods of characterization 5 6 Reference conditions for characterization 8 7 Test procedures 8 8 Results 11 9 Test report 12Page 3 EN 1518:1998 BSI 1998 1 Scope This
18、European Standard specifies terms and procedures for the characterization of mass spectrometer leak detectors (MSLD). It is not intended to give a complete set of specifications for an acceptance test but a description of procedures that can be used without particular calibration equipment. An MSLD
19、has an integral high vacuum system for maintaining the sensing element (mass spectrometer) at low operating pressure and for establishing a partial pressure related to the incoming gas flow. This pressure is measured quantitatively by the mass spectrometer. Such instruments are able to selectively m
20、easure the flow of a tracer gas. In most cases the tracer gas will be helium, flowing in/out of an object through a leak. The methods described in this standard are applicable without restrictions to helium as the tracer gas. For other gases, additional precautions may be necessary. These methods ar
21、e applicable to commonly-available MSLD, based on the present level of technology, which may be able to measure leak rates down to 10 212 Pam 3 /s. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references
22、 are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the lates
23、t edition of the publication referred to applies. prEN 1330-8, Non-destructive testing Terminology Part 8: Terms used in testing for leak tightness. 3 Definitions For the purposes of this standard, the definitions given in prEN 1330-8 apply together with the following. 3.1 Terms 3.1.1 compression ra
24、tio of the counterflow stages of the high vacuum pump for tracer gas with zero flow, the ratio of partial pressure of tracer gas at the exhaust of the counterflow stages of the high vacuum pump to the partial pressure at the inlet of the mass spectrometer (MS) 3.1.2 display a device which indicates
25、visually the leakage rate measured. The units in which the leakage rate is expressed may be selectable NOTE The display may be analog or quasi-analog (continuous scale with definite divisions) or digital (numbers with a definite number of digits) or a combination of both. 3.1.3 inlet pumping speed t
26、he volume rate of flow at the test port of an MSLD when the instrument is operating with the MS below its maximum working pressure NOTE The inlet pumping speed may be different for different gases and different modes of operation. The inlet pumping speed for the tracer gas determines the response ti
27、me for the volume under test. 3.1.4 internal leak port a flange directly behind the inlet valve, used to connect a small leak for zero drift determination 3.1.5 intrinsic pumping speed in a direct flow leak detector, the volume rate of flow of tracer gas at the inlet of the MS 3.1.6 ion collector th
28、e part of the MS where ions are collected and neutralized producing a current in the collector which is a measure of the number of neutralized ions 3.1.7 sensitivity control an electrical hardware or software control which may be used to adjust the sensitivity of the instrument so that a calibrated
29、leak is indicated with its true leakage rate 3.1.8 sensitivity of the MS the ratio of the ion current at the output of the MS to the corresponding partial pressure of tracer gas inside the MS 3.1.9 zero control an electrical hardware or software control which may be used to shift the output indicati
30、on of the leak detector to a determined point of the scale range in use, usually zero 3.2 Terms related to the operation of the MSLD 3.2.1 peak (noun) the trace showing a maximum on the chart recorder when the leak detector is scanned with respect to mass with gas present, usually the tracer gas, to
31、 which the detector is tuned 3.2.2 peak (verb) to set the scanning control (see 3.2.3) of a leak detector so that the output due to a given tracer gas input is maximized. It is a form of tuning (see 3.2.4)Page 4 EN 1518:1998 BSI 1998 3.2.3 scan (verb) to adjust the accelerating voltage (or other equ
32、ivalent operating parameter) of a leak detector, particularly across that range of voltage which includes the voltage necessary to produce a tracer gas peak 3.2.4 tune (verb) in leak detection, to adjust one or more of the controls of a leak detector so that its response to a tracer gas is maximized
33、. Tuning by means of the scanning control only is called “peaking” (see 3.2.2) 3.3 Terms related to the specification of the MSLD 3.3.1 Operating conditions 3.3.1.1 General For the definition of operating conditions see prEN 1330-8. NOTE The operating conditions are normally given by the manufacture
34、r. 3.3.1.2 optimum working pressure the pressure in the MS, at which the minimum detectable concentration can be measured 3.3.1.3 maximum working pressure the pressure in the MS above which normal operation is no longer possible 3.3.1.4 maximum inlet pressure the maximum pressure at the test port at
35、 which the MSLD is able to detect leaks in a given mode of operation NOTE For an MSLD to be connected directly to a system under test, the total pressure in the system has to be less than the maximum inlet pressure of the MSLD. 3.3.1.5 maximum gas load the maximum pV-throughput of all gases emerging
36、 from the test specimen that the MSLD can pump during leak detection in a given mode of operation NOTE For component testing, the MSLD is normally ready for measurement when the desorption of water vapour from the inner surfaces is less than the maximum gas load. 3.3.2 Tracer gas background signal 3
37、.3.2.1 background signal drift the relatively slow change in background signal, given by the maximum change in a given period of time 3.3.2.2 background signal noise the relatively rapid change in background signal given by an average measure of scatter in a specified period of time 3.3.3 Detection
38、limit 3.3.3.1 minimum detectable concentration ratio the smallest concentration of a given tracer gas in an air mixture that can be detected unambiguously when the mixture is fed into the MSLD at such a rate as that is at its optimum working pressure 3.3.4 resolving power the ratio of a given mass n
39、umber to the peak width measured at a specified (for example 10 %) height of the peak (in units of mass numbers) 3.3.5 Display resolution 3.3.5.1 general a quantitative expression of the ability of the leakage rate-display device to distinguish meaningfully between closely adjacent values of the lea
40、kage rate indicated 3.3.5.2 linear display resolution the constant difference between adjacent scale intervals expressed in % full scale indication 3.3.5.3 logarithmic display resolution the constant ratio between two adjacent scale intervals expressed as a percentage of the indicated value 4 Descri
41、ption of an MSLD 4.1 Main parts of an MSLD An MSLD (see definition given prEN 1330-8) consists basically of a mass spectrometer and a high vacuum pumping system for: maintaining the MS under appropriate vacuum conditions; producing a definite partial pressure of tracer gas when a specific throughput
42、 of tracer gas enters the leak detector. An MSLD includes also a number of valves and pressure gauges to ensure the appropriate vacuum conditions within the system. The leakrate output can be displayed in a number of ways, for example an electrical meter, or digital displays of different types. In a
43、ddition, a chart recorder output is usually available, which has to be used for the test procedures in this standard.Page 5 EN 1518:1998 BSI 1998 The general structure of an MSLD is described by the following list. a) Mass spectrometer: ion source; separation system; ion collector. b) Pumping system
44、: inlet system; inlet line; inlet valve; pump valve; test port; vent valve; internal leak port. c) Sensitivity zero control. d) Display. 4.2 Operating principles of MSLD 4.2.1 Direct flow leak detectors The leakage rate q x is given by the equation: q x = p x 3 S x where q x is the pV-throughput of
45、tracer gas; S x is the intrinsic pumping speed; p x is the partial pressure of tracer gas in the mass spectrometer (MS). 4.2.2 Counterflow leak detectors The leakrate q x is given by the equation: q x = p x 3 K x 3 S b,x where q x is the pV-throughput of tracer gas; K x is the compression ratio of t
46、he counterflow stages of the high vacuum pump for tracer gas (see 3.1.1); S b,x is the speed of the pumping system, for tracer gas, backing the counterflow stages of the high vacuum pump; p x is the partial pressure of tracer gas in the MS. 4.3 MLSD specification The MLSD specification is described
47、by the following list: a) Operating conditions: optimum working pressure; maximum working pressure; maximum inlet pressure; maximum gas load. b) Tracer gas background signal: background signal drift; background signal noise. c) Non linearity. d) Detection limit: minimum detectable leakage rate; mini
48、mum detectable concentration ratio. e) Resolving power. f) Display discrimination. 5 Apparatus for methods of characterization 5.1 Leaks For the following tests, two known leaks are required: a small tracer gas leak for the test of minimum detectable leakage rate; a large air leak for the determinat
49、ion of minimum detectable concentration. Both leaks have to have a specified temperature correction. For MSLD using the working principles indicated by 4.2.1 and 4.2.2, depending on measurement range, more than two leaks may be necessary for determination of detection limits and sensitivity according to the working principle. 5.1.1 Small tracer gas leaks The small known leaks shall be of a size such that the total pressure in the MS is negligibly increased. For the determination of
