© ISO 2017 Non destructive testing — Leak testing — Vocabulary Essais non destructifs — Contrôle d’étanchéité — Vocabulaire INTERNATIONAL STANDARD ISO 20484 First edition 2017 03 Reference number ISO[.]
INTERNATIONAL STANDARD ISO 20484 First edition 2017-03 Non-destructive testing — Leak testing — Vocabulary Essais non-destructifs — Contrôle d’étanchéité — Vocabulaire Reference number ISO 20484:2017(E) © ISO 2017 ISO 20484:2017(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO 20484:2017(E) Contents Page Foreword iv Introduction v Scope Normative references Terms and definitions 3.1 Atomic/molecular structure 3.2 Pressure and vacuum 3.3 Gas-solid interaction Terms relating to gas 4.1 Properties of gases 4.2 Flow of gas Terms relating to test techniques 5.1 Test techniques 5.2 Test equipment 5.3 Test equipment components 6 Terms relating to test procedure 6.1 Preparation/calibration 6.2 Test techniques 6.3 Performance limits © ISO 2017 – All rights reserved iii ISO 20484:2017(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally carried out through ISO technical committees Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the voluntary nature o f standards, the meaning o f ISO specific terms and expressions related to formity assessment, as well as in formation about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso org/iso/foreword html ISO 20484 was prepared by the European Committee Standardization (CEN) Technical Committee CEN/TC 138, Leak testing, in collaboration with ISO Technical Committee TC 135, Non-destructive testing , Subcommittee SC 6, Leak testing , in accordance with the agreement on technical cooperation between ISO and CEN (Vienna Agreement) This document is based on and replaces the European standard EN 1330-8:1998, Non-destructive testing — Terminology — Part 8: Terms used in leak tightness testing iv © ISO 2017 – All rights reserved ISO 20484:2017(E) Introduction The series o f European standards, EN 1330, comprises 10 parts prepared separately by groups o f experts, each group consisting of experts in a given NDT (non-destructive testing) method (for EN 13303 to EN 1330-10) A comparative examination of these parts has shown the existence of common terms that are often defined di fferently These terms have been taken from EN 1330-3 to EN 1330-10 and then split into two categories: — general terms corresponding to other fields such as physics, electricity, metrology, etc and already defined in international documents; these terms are the subject o f EN 1330-1; — common terms specific to NDT; these terms, the definitions o f which have been harmonized in an Ad Hoc group, are the subject o f EN 1330-2 In view o f the nature o f the approach taken, the list o f terms in EN 1330-1 and EN 1330-2 are in no way exhaustive EN 1330 consists of the following parts: — Part 1: General terms — Part 2: Terms common to the non-destructive testing methods — Part 3: Terms used in industrial radiographic testing — Part 4: Terms used in ultrasonic testing — Part 7: Terms used in magnetic particle testing — Part 9: Terms used in acoustic emission — Part 10: Terms used in visual examination NOTE ISO 12718 replaced EN 1330–5 NOTE ISO 12706 was published formerly as the dra ft European standard prEN 1330–6 © ISO 2017 – All rights reserved v INTERNATIONAL STANDARD ISO 20484:2017(E) Non-destructive testing — Leak testing — Vocabulary Scope T h i s c ument defi ne s the term s u s e d i n le a k te s ti ng Normative references There are no normative references in this document Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at http://www.iso org/obp — IEC Electropedia: available at http://www.electropedia org/ 3.1 Atomic/molecular structure 3.1.1 concentration c ratio of the number of atoms or molecules of a given constituent in a gas mixture to the total number of atoms or molecules in the mixture N o te to entr y: For ide a l ga s e s , th i s i s e qu iva lent to the ratio o f the p a r ti a l pre s s u re to the to ta l pre s s u re N o te to entr y: I n o ther c a s e s , the concentration i s co n s idere d a s mo le frac tion a nd the s ymb ol u s e d i s 3.1.2 ionization potential m i n i mu m energ y, e xpre s s e d i n ele c tronvolts , re qu i re d to remove an ele c tron or ion to form a positive ion from nB an atom or mole c u le 3.2 Pressure and vacuum 3.2.1 atmospheric pressure pre s s u re o f the atmo s phere at a s p e ci fie d place a nd ti me 3.2.2 partial pressure pA , p B pre s s u re that wou ld b e e xer te d by a ga s or vap ou r i f it a lone wa s pre s ent i n a n enclo s u re 3.3 Gas-solid interaction 3.3.1 gettering remova l o f a ga s by p ermanent bi nd i ng i n or on a s ol id, u s ua l ly i nvolvi ng chem ic a l re ac tion © ISO 2017 – All rights reserved ISO 20484:2017(E) 3.3.2 occlusion of gas trapping o f undissolved gas in a solid during solidification 3.3.3 permeation mechanism of adsorption/solution/diffusion/desorption in a solid material that allows a substance to pass through under a partial pressure difference 3.3.4 p e r m e a b i l i t y Pperm c o e f f i c i e n t coe fficient, dependent on temperature, characterizing the permeation (3.3.3) of a given substance conductance (4.2.1) of a material for the Terms relating to gas 4.1 Properties of gases 4.1.1 ideal gas perfect gas gas obeying the relationship pV = nRT, where n = m/M where p is the pressure; V is the volume; m is the mass o f the gas; M is the molecular mass; R is the ideal gas constant; T is the absolute temperature 4.2 Flow of gas 4.2.1 conductance C throughput divided by the di fference in mean pressures prevailing at two specified cross-sections or at either sides o f the duct or orifice, assuming isothermal conditions Note to entry: Applies to fluid flow in a duct, or part o f a duct, or a constriction 4.2.2 , , rate at which an amount of mass, a number of particles or moles pass through a given cross section of f l o w r a t e qM qN q ν the system Note to entry: Mass: qM , Particles: qN , Molar: q ν Note to entry: For gases, the volume flow rate (Volume: symbol q v) is a measure o f quantity only at specified conditions © ISO 2017 – All rights reserved ISO 20484:2017(E) 4.2.3 pV-throughput qG rate at wh ich a volu me o f gas at s p e c i fie d pre s s u re p as s e s a given c ro s s s e c tion o f the s ys tem N o te to entr y: I n le a k de te c tio n , pV-th rou ghp ut i s u s e d to e xpre s s the flow rate o f ga s T he temp eratu re a nd mo l a r weight or den s ity a re given add ition a l l y s o th at the flow rate c a n b e c a lc u l ate d u s i ng the ga s e qu ation 4.2.4 r e s i s t a n c e t o f l o w w re c ipro c a l o f conduc ta nce (flow) 4.2.5 d y n a m i c v i s c o s i t y η c o e f f i c i e n t co e ffic ient, dep endent on temp eratu re, that defi ne s the re s i s tance o f a s p e ci fie d flu id to the mo tion, due to the molecular interactions 4.3 Gas leakage 4.3.1 leak < non- de s truc tive te s ti ng (N D T ) > o f a n obj e c t a l lowi ng gas to p a s s hole, from p oro s ity, p erme able element or o ther s truc tu re in the wa l l one s ide o f the wa l l to the o ther by the e ffe c t o f pre s s u re - or concentration-difference across the wall 4.3.2 conductance leak le a k wh ich s i s ts o f one or more d i s c re te p a s s age s , i nclud i ng p orou s are as , th rough wh ich a flu id may flow 4.3.3 o r i f i c e l e a k conductance leak (4.3.2) having a diameter much greater than the leakage path length N o te to entr y: I t m ay a l s o b e s idere d a s a n op en i ng i n a ver y th i n wa l l 4.3.4 capillary leak conductance leak (4.3.2) in which the diameter is small compared to the length 4.3.5 leakage rate pV-th roughput o f a s p e ci fic flu id wh ich p a s s e s th rough a le a k u nder s p e ci fic cond ition s 4.3.6 leaktight object obj e c t with a le a kage rate lower th an that s tate d i n a s p e ci fic ation 4.3.7 molecular leak le a k o f s uch ge ome tric figuration a nd u nder s uch pre s s ure cond ition s that gas flowi ng th rough it ob eys the laws o f mole c u lar flow © ISO 2017 – All rights reserved ISO 20484:2017(E) 4.3.8 standard leakage rate leakage rate of a leak with stated standard temperature and pressure at one end and, at the other end, a pressure low enough to have a negligible effect on the leakage rate N o te to entr y: D i fferent s ta nd a rd pre s s u re - a nd temp eratu re cond itio n s a re u s e d [e g s ta nda rd temp eratu re and pressure (STP), standard ambient temperature and pressure (SATP)] 4.3.9 permeation leak le a k wh ich p erm its a gas to flow th rough a non-p orou s wa l l 4.3.10 total leakage rate integral leakage rate s u m o f a l l le a kage rate s from a l l le a ks o f an obj e c t, e xpre s s e d a s a pV-th roughput 4.3.11 virtual leak app arent (no t re a l) le a k, c au s e d b y me ch an i s m s generati ng a s igna l e qu iva lent to a le a kage rate s igna l N o te to entr y: S uch me ch a n i s m s c a n b e due to , fo r e xa mp le , temp eratu re a nd volu me e ffe c ts or s low rele a s e o f sorbed or occluded gases from surfaces or from the bulk of the material 4.3.12 viscous leak le a k o f s uch ge ome tric figu ration and under s uch pre s s u re cond ition s that ga s flowi ng th rough it ob eys the l aws o f vi s cou s flow Terms relating to test techniques 5.1 Test techniques 5.1.1 accumulation test le a kage te s t where a tracer gas i s col le c te d i n a known volume over a s p e c i fie d p erio d o f ti me and the partial pressure (3.2.2) increase of the tracer gas is measured N o te to entr y: T he le a kage rate c a n b e o b ta i ne d b y c a l ib rati ng the p a r ti a l p re s s u re r i s e with th at due to a known leak or comparing the measured concentration (3.1.1) with a known concentration 5.1.2 carrier gas test f l u s h i n g t e s t le a kage te s t i n wh ich a vi s cou s gas flow i s cre ate d a long the outer s u r face o f the te s t obj e c t i n a chamb er to c a rr y e s c api ng tracer ga s to the s en s or 5.1.3 vacuum tracer gas test leakage tes t in which tracer gas is detec ted in a s pace where the tracer gas atoms move freely to the sensor N o te to entr y: E ach tracer ga s s p e c ie s mo ve s with its s p e c i fic therm a l velo c ity 5.1.4 bombing test back-pressurising test le a kage te s t i n wh ich s e a le d obj e c ts are s ubj e c te d to pre s s u ri z ation with tracer ga s prior to te s ti ng them in a vacuum chamber © ISO 2017 – All rights reserved ISO 20484:2017(E) 5.1.5 bubble test leakage test used to detect leaks by the immersion o f the object in a test fluid or covering its outer surface with a surfactant (foaming) solution Note to entry: The pressure di fference across the walls o f the object is high enough that leaks are shown by bubble formation 5.1.6 hood test over-all leakage test in which the object is placed in a so ft enclosure at atmospheric pressure (3.2.1) Note to entry: I f the object is evacuated, the enclosure is filled with tracer gas and the leak detector is connected to the inner volume o f the object Note to entry: I f the object is pressurized with the tracer gas, the test is per formed with the sampling probe inserted in the hood 5.1.7 pressure change test leakage test in which the rate o f the total pressure change (decay or rise) in an object is measured over a period of time 5.1.8 leakage test in which the flow is measured necessary to maintain a pressure di fference across the object boundary f l o w m e a s u r e m e n t t e s t Note to entry: The upstream pressure may be controlled by pressure regulator or an auxiliary volume 5.1.9 pressure dye test leakage test in which a liquid containing a dye or fluorescent oil is driven by a pressure di fferential into the leak in the wall o f the object to be tested and is then detected by a visual inspection on the other side 5.1.10 chemical reaction test leakage test in which the outside o f the test object is probed with a reactive substance showing a reaction when in contact with escaping fluid Note to entry: A typical example for the reaction may involve the colour change o f an indicator 5.1.11 radionuclide leakage test leakage test which uses a radioactive tracer fluid and a detector for measuring the radiation emitted by the tracer fluid 5.2 Test equipment 5.2.1 tracer gas leak detector instrument capable of detecting and measuring pV-throughputs (4.2.3 ) of a specific tracer gas with acceptable response time Note to entry: A gas sensor is too slow and a flow meter is not sensitive enough to be a tracer gas leak detector 5.2.2 mass spectrometer leak detector in which the tracer gas (helium or hydrogen) enters through the c o u n t e r f l o w h e l i u m l e a k d e t e c t o r backing line into the outlet port of the high vacuum pump and the partial pressure of the tracer gas is measured on the high vacuum side of this pump © ISO 2017 – All rights reserved ISO 20484:2017(E) 5.2.3 mass spectrometer leak detector in which the tracer gas enters the high vacuum side of the pump d i r e c t f l o w l e a k d e t e c t o r s ys tem where the p ar tia l pre s s u re o f tracer ga s i s me as u re d 5.2.4 differential Pirani gauge le a k de te c tor, i n wh ich the ga s com i ng from the te s t obj e c t or a s a mpl i ng prob e enters one o f two s i m i la r P i ran i tub e s (therma l conduc tivity gauge s) b ei ng arm s i n a Whe ats tone bridge 5.2.5 discharge tube leak indicator glas s tub e, l i n ke d to the vac uum s ys tem to b e te s te d, i n wh ich the gas pre s ent i n the s ys tem i s e xp o s e d to a h igh fre quenc y ele c tric a l d i s ch arge N o te to entr y: S h ap e a nd co lo u rs o f the d i s ch a rge a re rel ate d to the n atu re a nd p re s s u re o f the ga s pre s ent i n the s ys tem 5.2.6 halogen leak detector leak detector that is sensitive to halogen tracer gas N o te to entr y: E xa mp le s a re a l ka l i-ion d io de - , i n fra re d- , fl a me -ion i z atio n- a nd ele c tro n- c ap tu re de te c tor 5.2.7 helium leak detector leak detector that is sensitive to helium (4He) tracer gas 5.2.8 mass spectrometer leak detector MSLD leak detec tor in which the sens ing element is a mas s s p ec trometer, tuned to res pond only to the tracer gas 5.2.9 spark coil leak tester h igh fre quenc y d i s charge coi l o f the Te s la typ e wh ich i nd ic ate s pi n hole s i n a gla s s vac uum s ys tem b y a s p ark j u mpi ng b e twe en the core o f the coi l a nd the pi n hole 5.2.10 ultrasonic leak tester s en s or th at de te c ts u ltra s onic s ou nd pro duce d b y the flow o f a ga s or l iqu id th rough a (4.3.2) and which converts this to a usable signal conductance leak 5.3 Test equipment components 5.3.1 sampling probe device u s e d to col le c t tracer gas reduced pressure required from a n are a o f the te s t obj e c t and tra n s fer it to the le a k de te c tor at the 5.3.2 spray gun device for d i re c ti ng a fi ne j e t o f tracer gas on a n obj e c t u nder vac uu m te s ti ng 5.3.3 test seal temp orar y s e a l on ly u s e d for the te s t, e g plugs or ga s ke ts , o ther th an op erati ng s e a l s © ISO 2017 – All rights reserved ISO 20484:2017(E) 5.3.4 tight chamber < non- de s truc tive te s ti ng (N D T ) > tight enclo s u re that c a n comple tely contai n the obj e c t to b e te s te d and th at c an b e pre s s u ri z e d or evac uate d to c re ate a pre s s ure d i fferenti a l ac ro s s the obj e c t wa l l 5.3.5 t r a c e r f l u i d flu id (ga s , l iqu id) wh ich c an b e de te c te d b y a s p e ci fic de te c tor and thu s d i s clo s e s the pre s ence o f a le a k 5.3.6 vacuum box conta i ner, op en at one s ide, wh ich ca n b e tightly fitte d to the wa l l to b e te s te d and u s e d a s a lo c a l vacuum chamber for partial tests N o te to entr y: For the p er for m a nce o f a bub b le te s t, the co nta i ner wa l l s a re tra n s p a rent Terms relating to test procedure 6.1 Preparation/calibration 6.1.1 calibrated leak le a k device wh ich provide s a known mas s rate o f flow traceable to national metrological standards for a s p e c i fic gas u nder s p e ci fic cond ition s , 6.1.2 reference leak calibrated leak comparison (6.1.1 ) i ntende d to b e u s e d as a re ference for the c a l ibration o f o ther le a k device s b y 6.1.3 adjustment of leak detector set of operations carried out on a leak detector so that it provides prescribed indications corresponding to given values of a leakage rate to be measured 6.1.4 operating conditions s p e ci fie d va lue s (u nder re ference cond ition s) dep endent on the s ys tem and on the ga s e s i nvolve d, wh ich sh a l l b e mai ntai ne d i n the s ys tem to p er form the te s t with a given i n s tr ument 6.1.5 pump-down time ti me re qu i re d to re duce the pre s s ure i n a s ys tem from atmospheric pressure (3.2.1) to the desired value 6.1.6 response factor relative s en s itivity o f a le a k de te c tor for a given ga s , comp a re d to a re ference ga s 6.1.7 response time time from the beginning of application of tracer gas until the signal reaches 90 % of the equilibrium s igna l, ob ta i ne d when the tracer gas i s conti nuou s ly appl ie d N o te to entr y: E xp onenti a l s ign a l s c a n b e de s c r ib e d b y a ti me co n s ta nt (s e e I S O 0) 6.1.8 test conditions actual conditions of ambient temperature and pressure under which the leakage test is performed © ISO 2017 – All rights reserved ISO 20484:2017(E) 6.1.9 zero adjustment adj u s tment o f the z ero control s o that the output i nd ic ation o f the le a k de te c tor i s at the zero o f the indicating scale or at some other reference point 6.2 Test techniques 6.2.1 backing-line port technique me tho d o f te s ti ng i n wh ich the le a k de te c tor i s ne c te d to a p or t i n the b acki ng , l i ne o f the s ys tem under test 6.2.2 bombing ac tion o f s ubj e c ti ng s e a le d te s t obj e c ts to a h igh pre s s u re o f te s t gas (u s ua l ly hel iu m) 6.2.3 dynamic leakage rate measurement le a kage te s t where the le a kage rate i s de term i ne d b y me as u ri ng the e qu i l ibriu m (s te ady- s tate) (3.2.2 pressure partial ) o f the tracer gas wh i le the s ys tem i s b ei ng pu mp e d 6.2.4 isolated pressure test pre s s u re te s t where the obj e c t i s i s olate d from the pumpi ng or pre s s u ri z i ng s ys tem s o that the pre s s u re change s i n the te s t obj e c t i f a le a k exi s ts 6.2.5 masking coveri ng o f p a r t o f a te s t obj e c t to prevent tracer ga s enteri ng le a ks that may e xi s t i n that p ar t 6.2.6 s n i f f i n g t e s t le a kage te s t i n wh ich the obj e c t u nder te s t i s pre s s u ri z e d with tracer ga s a nd the e s c api ng tracer gas th rough le a ks i s de te c te d b y a s a mpl i ng (s ni ffer) prob e 6.2.7 vacuum test te s t u s e d to de te c t le a kage from a n evac uate d obj e c t ne c te d to a mas s s p e c trome ter le a k de te c tor by plac i ng it i n a tight cha mb er fi l le d or pre s s u ri z e d with tracer gas 6.3 Performance limits 6.3.1 clean up time time, from the end of application of tracer gas, until the signal falls to 10 % of the equilibrium signal, ob tai ne d when the tracer ga s was conti nuou sly appl ie d N o te to entr y: E xp onentia l s ign a l s c a n b e de s c rib e d b y a ti me s ta nt (s e e I S O 0) 6.3.2 detection limit of leakage test s ma l le s t le a kage rate th at c an b e rep e atably de te c te d u nder s p e ci fie d cond ition s 6.3.3 instrument signal drift gradual change of an instrument output signal due to changes in the ambient conditions or in the electronics © ISO 2017 – All rights reserved ISO 20484:2017(E) 6.3.4 tracer gas drift gradual change of the output signal of the leak detector, due to changes in tracer gas partial pressure at the sensor 6.3.5 minimum detectable leakage rate s ma l le s t le a kage conditions rate that c an be de te c te d u nambiguou s ly b y a le a k de te c tion s ys tem u nder te s t 6.3.6 minimum detectable signal output signal, due to the incoming tracer gas which is equal to the sum of the noise and the drift per s p e ci fie d ti me o f the s igna l N o te to entr y: T he m i n i mu m de te c tab le s ign a l i s given i n u n its o f the i n s tr u ment output, e g s c a le d ivi s io n s , voltage 6.3.7 background signal to ta l s pu riou s i nd ic ation given b y the le a k de te c tion s ys tem at the s tar ti ng p oi nt o f the te s t (without i nj e c ti ng tracer ga s) © ISO 2017 – All rights reserved ISO 0484: 01 7(E) I C S ; 0 Price Code A © ISO 2017 – All rights reserved