1、BRITISH STANDARD BS 1796-1: 1989 ISO 2591-1: 1988 Test sieving Part 1: Methods using test sieves of woven wire cloth and perforated metal plateBS1796-1:1989 This British Standard, having been prepared under the directionof the General Mechanical Engineering Standards Policy Committee, waspublished u
2、nder the authorityof the Board of BSIandcomes into effect on 29 September1989 BSI 01-2000 First published March1952 First revision July1976 Second revision September1989 The following BSI references relate to the work on this standard: Committee reference GME/29 Draft for comment87/71699DC ISBN 0 58
3、0175278 Committees responsible for this BritishStandard The preparation of this British Standard was entrusted by the General Mechanical Engineering Standards Policy Committee (GME/-) to Technical Committee GME/29, upon which the following bodies were represented: BCIRA British Cement Association Br
4、itish Ceramic Society British Coal Corporation British Laboratory Ware Association Coated Abrasives Manufacturers Association Department of Transport Guild of Metal Perforators Institution of Chemical Engineers Institution of Mining and Metallurgy Mechanical Handling Engineers Association Ministry o
5、f Defence NABIM Society of Chemical Industry Society of Cosmetic Scientists Woven Wire Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Aluminium Federation British Ceramic Research Ltd. Chemical Industries Association Departme
6、nt of Trade and Industry (Warren Spring Laboratory) English Metal Powder Co. Ltd. Institute of Physics Institution of Mining Engineers Oil and Colour Chemists Association Royal Society of Chemistry University of Bradford Amendments issued since publication Amd. No. Date of issue CommentsBS1796-1:198
7、9 BSI 01-2000 i Contents Page Committees responsible Inside front cover National foreword ii 0 Introduction 1 1 Scope and field of application 2 2 References 2 3 Definitions 2 4 Material to be sieved 2 5 Sampling 3 6 Apparatus 4 7 Test sieving methods 4 8 Presentation of results 9 Figure 1 Example o
8、f a completed test results form 10 Figure 2 Example of graphical presentation of test sieving results (cumulative undersize graph) on linear coordinates 11 Figure 3 Example of graphical presentation of test sieving results (cumulative undersize graph) on linear/logarithmic coordinates 12 Figure 4 Ex
9、ample of graphical presentation of test sieving results (cumulative undersize graph) on probability/logarithmic coordinates 13 Table Guide to quantity of material for test sieving on a200mm diameter round sieve 6 Publications referred to Inside back coverBS1796-1:1989 ii BSI 01-2000 National forewor
10、d This Part of BS1796 has been prepared under the direction of the General Mechanical Engineering Standards Policy Committee. It is identical with ISO2591-1:1988 “Test sieving Part1: Methods using test sieves of woven wire cloth and perforated metal plate”, which is a revision of ISO2591:1973, prepa
11、red by Technical Committee ISO/TC24, Sieves, sieving and other sizing methods, of the International Organization for Standardization (ISO), and in the development of which the UK has played an active part. It supersedes BS1796:1976, which is withdrawn. Cross-references The Technical Committee has re
12、viewed the provisions of ISO565:1983 1) , ISO2395:1972 1) , ISO3310-1:1982 1) , ISO3310-2:1982 1)and ISO3310-3 2) , to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A related British Standard to ISO565:1983 1) , ISO3310-1:198
13、2 1)and ISO3310-2:1982 1)is BS410:1986“Specification for test sieves”. ISO 565:1983 1)is only referred to in clause0 and inFigure 1, and ISO2395:1972 1)is only referred to in clause2 for information. A British Standard does not purport to include all the necessary provisions of a contract. Users of
14、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 a front cover, an inside front cover, pages i and ii, pages1 to 14, an inside back cover and a back
15、cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) At present being revised by ISO. 2) At present at the stage of draft.BS1796-1:1989 BSI 01-2000 1 0 Introduction 0.1 General
16、 considerations Test sieving is used in many industries on a wide variety of materials and for different purposes. No single method of test sieving can be specified to cover the many applications, and certain industries have already produced specifications for sieving procedures which are incorporat
17、ed in the appropriate International Standard for a limited application. Standardized series of nominal openings of test sieve media are specified in ISO565, and standardized technical requirements on test sieves are standardized in ISO3310. ISO 2591 is intended as a guide to all who are responsible
18、for deciding on test sieving procedures, including those concerned with specific materials, and it formulates general principles of sieving which may be applied to many natural and artificial materials. The procedures given depend on the predominant size range of the particles in a sample, and it is
19、 recognized in this part of ISO2591 that some materials are difficult to sieve and require specially developed techniques (see clause4). Test sieving may be undertaken a) as part of a research project involving an investigation of the particle size of a material; b) as part of a control procedure fo
20、r the production of material where the particle size distribution is important; c) as the basis of a contract for the supply of material specified to be within stated grading limits. The principles to be followed in the sieving procedure will be similar in each case but the actual detail may vary co
21、nsiderably according to the purpose for which the results are required. For example, the main criterion for a sieve analysis undertaken for research purposes may be consistency in one laboratory, whereas for a procedure which forms part of a specification in a contract it may well be maximum reprodu
22、cibility between laboratories consistent with reasonable cost of testing. The accuracy required for quality control purposes may well be relatively low and the predominant factors could be low cost, maximum mechanization and speed in obtaining the result. A simplified procedure with a given operator
23、 and particular apparatus in one set-up may be found adequate for control purposes, even though the reproducibility of the procedure as used between different laboratories may not be very good. 0.2 Principles of sieving A single test sieve separates a particular material into two fractions, of which
24、 one is retained by the sieving medium and the other of which passes through its apertures. When applied to particles of non-spherical shape the procedure is complicated by the fact that a specific particle with a size close to that of the nominal aperture size of the test sieve may pass through the
25、 apertures only when presented in a favourable position, and will not pass through when presented in other positions. As there is inevitably a variation in the size of the sieve apertures, prolonged sieving will cause the larger apertures to exert an unduly significant effect on the sieve analysis:
26、the proportion of oversize apertures is limited by the specifications for test sieves. The procedure is also complicated in many cases by the presence of so-called “near aperture size” particles which cause blinding of the sieve apertures and reduce the effective area of the sieving medium. The proc
27、ess of sieving may be divided into two stages: firstly, the elimination of particles considerably smaller than the sieve apertures, which could occur fairly rapidly, and secondly, the separation of “near aperture size” particles, which is a gradual process rarely reaching completion. Both stages req
28、uire all particles put on the sieving medium to have the opportunity of passing through an aperture. Ideally, each particle should be presented individually to an aperture, as is permitted for the largest aperture sizes, but for most sizes this is impracticable. The effectiveness of a sieving techni
29、que depends on the amount of material (charge) put on a sieve and the type of movement imparted to the charge on the sieve. If the charge is too large, the bed of material on the sieving medium will be too many particles deep to allow each one the opportunity of being presented to an aperture in the
30、 most favourable position in order for gauging to be completed in a reasonable time. The charge, therefore, is limited by a requirement on the maximum amount of material retained at the end of sieving appropriate to the aperture size of the test sieve. However, the sample to be sieved has to contain
31、 enough particles to be representative of the consignment, so a minimum size of sample is specified. In some cases, the sample will have to be subdivided into a number of charges if the requirement for preventing overloading of the sieves is to be satisfied.BS1796-1:1989 2 BSI 01-2000 The movement i
32、mparted to a sieve by hand can be adapted, by experience, to meet the needs of the material and the sieving medium; different techniques are required for particles of quite different size. A machine, however, is usually designed to impart a particular combination of movements, irrespective of the ap
33、erture size of the test sieve or the characteristics of the material, and may not be readily adaptable to be equally effective for different materials. Nevertheless, a machine does not get tired and moderate effectiveness may often be acceptable providing that sieving continues long enough. When thi
34、s part of ISO2591 was being prepared, the alternatives of shaking the sieve by hand and by means of a machine were considered. Hand shaking by an experienced operator is generally more effective when sieving relatively coarse particles. For fine powders, however, the end point may be approached more
35、 rapidly, and certainly with less effort, by using one of the many mechanical and other sieving techniques now commercially available. Hand sieving and machine sieving are not mutually exclusive; machine sieving followed by a final brief hand sieving to ensure that the end point has been reached (se
36、e7.2.7) may achieve the best results. 0.3 Correlation of results from different methods of size analysis It may be necessary to combine size distributions determined by different methods, e.g. sieving, sedimentation, elutriation or microscopy. It is preferable to cover the range of a single distribu
37、tion using a single method, but this is not always possible. A simple, but admittedly not a particularly accurate, procedure for establishing correlation factors for two different sizing techniques is to overlap the methods of size determination so that one or more size classes are assessed by both
38、methods. 1 Scope and field of application This part of ISO2591 draws attention to and describes the main factors affecting test sieving and the results obtained; it also specifies general principles to be followed concerning apparatus, procedure and presentation of results. It applies to methods in
39、which test sieves of woven wire cloth or perforated metal plate are used. Test sieving methods using test sieves of electroformed sheet will form the subject of ISO2591-2. 2 References ISO 565, Test sieves Woven metal wire cloth, perforated plate and electroformed sheet Nominal sizes of openings. IS
40、O 2395, Test sieves and test sieving Vocabulary. ISO 3310, Test sieves Technical requirements and testing Part1: Test sieves of metal wire cloth Part 2: Test sieves of perforated metal plate Part3: Test sieves of electroformed sheets 3) . 3 Definitions For the purposes of this part of ISO2591, the d
41、efinitions given in ISO2395 apply. 4 Material to be sieved 4.1 General Materials to be test sieved range from very coarse lumps, such as coal and stone, to very fine materials, such as pigments and clay; they differ in their physical and chemical properties. Information about the properties of a mat
42、erial is helpful in judging its sieving characteristics, and should be noted in the test report. The more important properties affecting sieving are dealt with in4.2. Because of the considerable variety of material properties encountered, it is not possible to specify a single method of test sieving
43、 which applies to all materials. The sieving method appropriate to a material should be stated in an International Standard or national standard, or in other specifications dealing with that material. 4.2 Physical and chemical properties 4.2.1 Density The following kinds of density are important in
44、test sieving: a) effective particle density, which can affect the duration of sieving; b) apparent bulk density, which can influence the quantity of material to be taken for sieving. 4.2.2 Friable nature Some materials are liable to reduce in size during sieving because of their friable nature. This
45、 property should be taken into account in the handling of the material during sampling and test sieving. 3) At present at the stage of draft.BS1796-1:1989 BSI 01-2000 3 4.2.3 Abrasive properties Some materials, e.g. emery powders, are abrasive; these wear out the sieves and modify the apertures in t
46、he course of a prolonged sieving operation. It is desirable to ascertain whether or not the material is abrasive before commencing the test and to check the conformity of the apertures of the sieving medium against the specified tolerances. 4.2.4 Surface moisture Surface moisture is important becaus
47、e it affects the way in which a material will flow on a sieve. 4.2.5 Internal moisture If there is a change in internal moisture during sieving, the masses of the fractions will be affected. 4.2.6 Hygroscopic properties Some materials readily absorb moisture and cannot safely be allowed to come into
48、 equilibrium with the laboratory atmosphere. In such cases they should be handled and sieved in such a way as to reduce their contact with the atmosphere to a minimum. 4.2.7 Change of property on drying It is important to know whether the properties of a material are changed by any proposed drying p
49、rocess, e.g. whether the material is liable to break or to cake. 4.2.8 Particle shape The duration and results of sieving can be considerably affected by the shape of the particles. 4.2.9 Size distribution The range of particle size of the material is important in deciding the sieving procedure to be used (see clause7). 4.2.10 Cohesive property The spreading of the particles on the sieving medium depends on the cohesive nature of the material; this, in turn, depends on the inter-particle forces and increases with the fineness of the powder. 4.2.11 Magne
