1、BRITISH STANDARDBS ISO 16232-7:2007Road vehicles Cleanliness of components of fluid circuits Part 7: Particle sizing and counting by microscopic analysisICS 13.040.50; 43.180g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g
2、51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 16232-7:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 June 2007 BSI 2007ISBN 978 0 580 50922 3National forewordThis British Standard was published by BS
3、I. It is the UK implementation of ISO 16232-7:2007.The UK participation in its preparation was entrusted to Technical Committee MCE/22, Engines for road vehicles.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to inc
4、lude all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publicationAmd. No. Date CommentsReference numberISO 16232-7:2007(E)INTERNATIONAL STANDARD ISO1
5、6232-7First edition2007-06-01Road vehicles Cleanliness of components of fluid circuits Part 7: Particle sizing and counting by microscopic analysis Vhicules routiers Propret des composants des circuits de fluide Partie 7: Dtermination et comptage des particules par analyse microscopique BS ISO 16232
6、-7:2007ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principles. 2 5 Equipment . 2 5.1 Equipment for the preparation of membrane filters 2 5.2 Analysis equipment 3 5.3 Image analysis 7 5.4 Motorized sample stage . 8 5.5 Multiple im
7、age analysis 8 5.6 Environmental conditions 9 5.7 Health and Safety 9 6 Calibration . 9 7 Procedure 10 7.1 Cleaning and preparing of equipment 10 7.2 Preparation of the membrane filter . 10 7.3 Particle sizing and counting procedure . 11 8 Results . 12 8.1 Test report . 12 8.2 Report the results . 1
8、2 Annex A (informative) Filtration 13 Annex B (informative) Field scanning 14 Annex C (informative) Particle counting on the margin. 15 Annex D (informative) Multiple image analysis. 18 Annex E (informative) Resolution and calibration of an image analysis system 19 Annex F (informative) Example of a
9、 test report 20 Bibliography . 22 BS ISO 16232-7:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees
10、. 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 Intern
11、ational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Sta
12、ndards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subj
13、ect of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16232-7 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 5, Engine tests. ISO 16232 consists of the following parts, under the general title Road vehicles Cleanline
14、ss of components of fluid circuits: Part 1: Vocabulary Part 2: Method of extraction of contaminants by agitation Part 3: Method of extraction of contaminants by pressure rinsing Part 4: Method of extraction of contaminants by ultrasonic techniques Part 5: Method of extraction of contaminants on func
15、tional test bench Part 6: Particle mass determination by gravimetric analysis Part 7: Particle sizing and counting by microscopic analysis Part 8: Particle nature determination by microscopic analysis Part 9: Particle sizing and counting by automatic light extinction particle counter Part 10: Expres
16、sion of results BS ISO 16232-7:2007vIntroduction The presence of particulate contamination in a fluid system is acknowledged to be a major factor governing the life and reliability of that system. The presence of particles residual from the manufacturing and assembly processes will cause a substanti
17、al increase of the wear rates of the system during the initial run-up and early life, and may even cause catastrophic failures. In order to achieve reliable performance of components and systems, control over the amount of particles introduced during the build phase is necessary, and measurement of
18、particulate contamination is the basis of control. The ISO 16232 series has been drafted to fulfil the requirements of the automotive industry, since the function and performance of modern automotive fluid components and systems are sensitive to the presence of a single or a few critically sized par
19、ticles. Consequently, ISO 16232 requires the analysis of the total volume of extraction liquid and of all contaminants collected using an approved extraction method. The ISO 16232 series has been based on existing ISO International Standards such as those developed by ISO/TC 131/SC 6. These Internat
20、ional Standards have been extended, modified and new ones have been developed to produce a comprehensive suite of International Standards to measure and report the cleanliness levels of parts and components fitted to automotive fluid circuits. This part of ISO 16232 defines methods of microscopic ex
21、amination to determine the particle size distribution of contaminants which have been removed from the component under analysis and collected using an approved extraction method. BS ISO 16232-7:2007blank1Road vehicles Cleanliness of components of fluid circuits Part 7: Particle sizing and counting b
22、y microscopic analysis 1 Scope This part of ISO 16232 defines methods for determining the size and number of contaminant particles, which have been extracted from components and deposited on the surface of a membrane filter, as determined by using either a light optical microscope (LM) or a scanning
23、 electron microscope (SEM). The result of this measurement is the particle size distribution on the membrane filter. As the function of parts and components can be impaired by the presence of a single or a few critical particles, a complete analysis of the total membrane filter surface is essential.
24、 These analyses can be performed either manually or automatically using Image Analysis (IA) techniques if the appropriate equipment is available. NOTE 1 Manual full-surface counting is a difficult and tiring task associated with errors. For this reason, an automatic counting system is recommended if
25、 the membrane filter is prepared in a suitable way as described herein. NOTE 2 The results of counting and sizing depend on many parameters, such as type and model of microscope, magnification, illumination, and other settings used. 2 Normative references The following referenced documents are indis
26、pensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 16232-1, Road vehicles Cleanliness of components of fluid circuits Part 1: Vocabulary ISO
27、 16232-2, Road vehicles Cleanliness of components of fluid circuits Part 2: Method of extraction of contaminants by agitation ISO 16232-3, Road vehicles Cleanliness of components of fluid circuits Part 3: Method of extraction of contaminants by pressure rinsing ISO 16232-4, Road vehicles Cleanliness
28、 of components of fluid circuits Part 4: Method of extraction of contaminants by ultrasonic techniques ISO 16232-5, Road vehicles Cleanliness of components of fluid circuits Part 5: Method of extraction of contaminants on functional test bench ISO 16232-10, Road vehicles Cleanliness of components of
29、 fluid circuits Part 10: Expression of results 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 16232-1 apply. BS ISO 16232-7:20072 4 Principles The entire volume of extraction liquid used to extract particles from the test component, as described in
30、ISO 16232-2, ISO 16232-3, ISO 16232-4 and ISO 16232-5, is filtered on a membrane filter and the separated particles are counted and sized using microscopic techniques. The longest dimension of a particle is used to determine particle size. Figure 1 Examples of longest dimension of a particle, X To d
31、etermine the particle size, a light microscope uses the optical contrast between the particle and the surface of the membrane filter. The contrast is mainly achieved by adjusting the intensity of illumination. The basis for counting particles using SEM is the material contrast which occurs as a resu
32、lt of the differing intensity of back-scattered electrons. NOTE Because the mechanisms of detection are based on different types of contrast, the counting results obtained from optical and scanning electron microscopy cannot be compared with one another. The filter and the analysis system are select
33、ed depending upon the amount of contamination expected and the relevant particle size range noted in the cleanliness specification. 5 Equipment 5.1 Equipment for the preparation of membrane filters 5.1.1 If necessary, a controllable non-ventilating oven capable of maintaining a temperature of 80 5 C
34、. 5.1.2 The membrane filter shall be compatible with the extraction liquid and any rinsing liquid or chemicals used in the processes. The pore size of the membrane filter shall be suitable for the minimum size of particles to be collected. The diameter of the membrane filter shall be large enough to
35、 avoid the contact or overlapping of particles which causes errors through coincidence. When using light microscopes, there should be a good optical contrast between the particles and the surface of the membrane filter. For scanning electron microscopy, a smooth-surfaced filter should be chosen (e.g
36、. polycarbonate, cellulose nitrate, cellulose acetate, polyamide). NOTE 1 Gridded membrane filters for assisting in orientation when counting particles manually with an optical microscope cannot be utilized for automated counting using image analysis. NOTE 2 To ease examination, it is recommended th
37、at the pore size of the membrane filter be less than 1/3 of the smallest particles to be analysed. BS ISO 16232-7:200735.1.3 There are two methods for separating the particles from the extraction liquid and these are described below: a) Membrane filter holder connected to the extraction equipment: T
38、he membrane filter holder device is directly fitted below the drain of the collection equipment. Several membrane filter holders may be mounted behind one another (cascade) to obtain a pre-selection of specific particle sizes during the filtration process. The equipment shall be designed so as to av
39、oid the settlement or loss of particles in the tubing. NOTE 1 A wider size range of pore sizes for pre-selection can be achieved using mesh type discs, either metallic or polymeric. If so then the filter disc holder should be carefully designed so that the discs can be easily extracted without losin
40、g particles. b) The extraction liquid is collected in a suitable vessel and then filtered using separate filtration apparatus made up of the following components: membrane filter holder base with suitably-sized funnel fixed with a clamp, vacuum flask possessing a capacity compatible with the entire
41、volume of the extraction liquid. The cleanliness of the filtration equipment shall be consistent to the presumed cleanliness of the component being tested. This is validated when performing the blank test. NOTE 2 If necessary the membrane filter holder should be earthed to avoid the build-up of elec
42、trostatic charge and subsequent discharge. NOTE 3 In the ISO 16232 series, the words “earthing” and “grounding” are synonymous. See Annex A for an example equipment diagram. 5.1.4 Use of a rinsing liquid as specified in the inspection document shall be compatible with all the equipment used in the p
43、rocess. 5.1.5 The source of rinsing liquid is specified in the inspection document. 5.1.6 The sputtering (coating by vacuum deposition) equipment is only necessary when using a SEM which requires a conducting film on the membrane filter. NOTE 1 Coating with carbon should be preferred to sputtering w
44、ith other elements, e.g. gold, silver. As the membrane filters are usually composed of organic materials, the carbon applied affects the measurement results much less than a layer of sputtered gold. NOTE 2 In some types of SEM charging can be reduced by reducing the vacuum but this can affect the re
45、solution in some designs. 5.1.7 Tweezers able to handle membrane filters without damaging them shall be used. 5.1.8 Vacuum device able to generate a vacuum of at least 65 kPa shall be used. 5.2 Analysis equipment 5.2.1 General 5.2.1.1 Figure 2 shows the equipment involved in microscopically counting
46、 particles on a membrane filter. In the process, differences occur between light-optical and scanning electron microscopes at the level of the lens and of the detectors. For both LM and SEM, computer-aided recording and counting image analysis techniques up to and including full-surface analysis are
47、 essentially identical. BS ISO 16232-7:20074 Figure 2 Diagrammatic representation of the microscopic analysis of membrane filters 5.2.1.2 The membrane filter (1) containing the particles extracted from the test component is placed on the sample stage and is imaged in magnified form by an optical sys
48、tem (2). In the case of the light microscope, this is done using a suitable light source that homogenously illuminates the field of view and the optical segment containing one or several objective lenses and an eyepiece. This is also the minimum configuration required for manual/visual counting and
49、sizing. In the case of a SEM, the sample is scanned by a focused high-energy electron beam in a vacuum chamber. 5.2.1.3 The optically-magnified information is gathered by a detector system (3), a video or digital camera in light microscopy and a detector which usually detects the back-scattered electrons with a high material contrast in SEM. The next step is performed by an image analyser (4) which separates the particles from the membrane filter background and measures and counts them using pre-given algorithms. Using the
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