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1、BRITISH STANDARD BS 1460:1967 Incorporating Amendment No. 1 Method for Determination of apparent density after compaction of precipitated calcium carbonate Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 This British Standard, h
2、aving been approved by the Chemicals Industry Standards Committee and endorsed by the Chairman of the Chemicals Divisional Council, was published under the authority of the General Council on 18 January 1967 BSI 09-1999 First published December 1948 First revision January 1967 The following BSI refe
3、rences relate to the work on this standard: Committee reference CIC/9 Draft for comment 66/1471 ISBN 0 580 35530 9 Co-operating organizations The Chemicals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives of the following Governmen
4、t departments and scientific and industrial organizations: Board of Trade British Iron and Steel Federation Chemical Industries Association* Fertilizer Manufacturers Association Gas Council Institute of Vitreous Enamellers Institution of Gas Engineers Ministry of Defence, Army Department Ministry of
5、 Health National Sulphuric Acid Association Royal Institute of Public Health and Hygiene The industrial organization marked with an asterisk in the above list, together with the following, was directly represented on the committee entrusted with the preparation of this British Standard: British Labo
6、ratory Ware Association British Paper and Board Makers Association (Incorporated) British Polish Manufacturers Association British Waterworks Association London Chamber of Commerce (Incorporated) Proprietary Association of Great Britain Toilet Preparations Federation Welwyn Hall Research Association
7、 Amendments issued since publication Amd. No.Date of issueComments 6199July 1967Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 BSI 09-1999i Contents Page Co-operating organizationsInside fr
8、ont cover Forewordii 1Scope1 2Apparatus1 3Procedure1 4Calculation2 Appendix Summary of results3 Figure 1 Dropping box4 Figure 2 Apparatus (assembled)5 Figure 3 Cylinder6 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 ii BSI 09-
9、1999 Foreword This standard makes reference to the following British Standards: BS 410, Test sieves. BS 903, Methods of testing vulcanized rubber Part A7: Determination of hardness. This British Standard was first issued in 1948, (under the authority of the Fine Chemicals Industry Standards Committe
10、e, now incorporated into the Chemicals Industry Standards Committee), when it was developed from a test which had been in industrial use for many years1). The method consists of ascertaining the bulk of a known mass of a prepared sample of precipitated calcium carbonate after compaction by a standar
11、dized procedure. Following a considerable amount, of discussion and joint testing by eleven collaborating laboratories, it proved possible at that time to set the method down in greater detail than had been previously possible and to declare the order of reproducibility of results which was to be ex
12、pected for different grades of precipitated calcium carbonate. In making these tests three grades of precipitated calcium carbonate, having apparent densities after compaction (g/ml) about 0.30 (Sample A), 0.50 (Sample B), and 0.80 (Sample C), were used. The results of the statistical analysis of th
13、e data obtained are set out in the Appendix. The inference drawn from these tests was that, provided the same operator made the determinations regularly without conscious variation of technique, the reproducibility of results obtainable, particularly in triplicate tests, was quite good, having regar
14、d to the known difficulties inherent in this type of test. When comparison of results obtained in different laboratories was considered, difficulty arose particularly with precipitated calcium carbonate such as Sample A. This was due to the fact that some feature of the test (probably associated wit
15、h the transfer of the sample to the cylinder, or to the methods of sieving the precipitated calcium carbonate), was not readily susceptible of description and standardization in such a way as to be perfectly repeatable by different operators. It was felt, however, that the issue of this standard met
16、hod would serve a useful purpose in eliminating avoidable discrepancies and, in conjunction with the statements made above, in drawing attention to the limitations inherent in the method and indicating the degree of accuracy that could be expected in practice. In the present revision, details of the
17、 apparatus, in particular of the cylinder, are given more specifically, as it has been found that the supply of suitable cylinders has proved a difficulty. All measurements have been given in metric units. In Figure 1 these should not be interpreted as requiring the apparatus to be made with more pr
18、ecision than is usual in such carpentry work and apparatus made to the original drawings is still suitable for use. Consideration has been given to the mechanization of the method, but no mechanical apparatus has been specified. Laboratories wishing to mechanize the procedure, should ensure that the
19、 apparatus faithfully copies the manual operations and that a suitable test programme is followed to show correspondence of results between the manual and mechanised methods. 1) Originally devised by Messrs. John and E. Sturge, Ltd. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT
20、+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 BSI 09-1999iii 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 immuni
21、ty from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 6 and a back 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 i
22、nside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 BSI 09-19991 1 Scope This British Standard de
23、scribes a method for the determination of apparent density after compaction of precipitated calcium carbonate. Although the method has been drafted to meet the special requirements for testing precipitated calcium carbonate, it is recognized that it is often applied to other powders. In these cases
24、it is necessary to assess the details of the test in relation to specific requirements, giving due consideration to the desired emphasis on discrimination between grades as against reproducibility. In this assessment it should be remembered that increasing the number of drops usually improves the re
25、producibility at the expense of discrimination, and consideration should be given to the possibility of using a different weight of test sample. For powders other than precipitated calcium carbonate it may be possible to relax some of the precisely defined conditions of handling the sample. NOTEIf t
26、est results are reported on such a modified test they should be accompanied by a statement in the form: “Tested generally in accordance with BS 1460, but using X g of sample and Y drops”. 2 Apparatus2) The apparatus required, the special parts of which are depicted diagrammatically in Figure 1, Figu
27、re 2 and Figure 3 comprises: a) Cylinder, glass with a solid base ground flat at right angles to the axis of the cylinder. It shall be graduated by 2 ml subdivisions over the range 20 ml to 250 ml. The graduations shall be permanently numbered at 10 ml intervals. The maximum permissible error in the
28、 graduations at any point shall be 0.6 ml provided that the difference between error at any two points does not exceed 0.6 ml. The internal depth from the 250 ml graduation mark to the base shall be 220 mm to 240 mm. The empty cylinder together with its rubber bung, shall weigh 250 5 g. b) Dropping
29、box, secured to a rigid bench or table. The distance between the flat ground base of the cylinder and the rubber base pad, when the cylinder is raised to the full height, shall be 25 1 mm, i.e. the total lift of the cylinder shall be corrected to 25 1 mm by suitable adjustment of the shelf. The rubb
30、er base pad shall have a nominal thickness of 56 mm and a hardness of 70 85 I.R.H.D.3) c) Timing device, to indicate seconds audibly. NOTEThis may conveniently be either a metronome or a stop clock. d) Balance or scales, of a type providing easy access to the pan or pans, which should be at least 10
31、0 mm in diameter. It is necessary that the pointer should show a significant deflection for a change in load of 0.25 g. e) Sampling paper, black glazed. f) Finger stalls, smooth rubber. g) Sieve4), nominal aperture width 500 microns, known as mesh number 30. 3 Procedure a) Weigh out approximately 42
32、 g of a fresh portion of the material on a piece of paper. b) Fold a piece of blank glazed sampling paper 250 250 mm with two parallel creases to form a channel 13 mm wide down the middle of the paper on its glazed side. Place this paper on the scale and counterpoise either with a similar sheet or b
33、y other suitable means. c) Place the sieve on the prepared paper on the bench, in such a manner that there is a 50 mm space between the gauze and the paper. d) Transfer the precipitated calcium carbonate to the sieve and with the back of the fingers fitted with rubber finger-stalls lightly rub all t
34、he calcium carbonate through the sieve, using a short stroke. If the sieve tends to clog, raise it about 25 mm and tap the edge lightly with the fingers (but not against the bench) e) Transfer the paper with the sieved sample to the balance and adjust the mass of the sample to 40 0.25 g. f) Pick up
35、the paper with the sieved sample and form it into a chute. 2) The special parts of the apparatus are available commercially from Messrs. Jencons (Scientific) Limited, Hemel Hempstead, England. 3) BS 903, “Methods of testing vulcanized rubber” Part A7: “Determination of hardness”. 4) BS 410, “Test si
36、eves”. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 2 BSI 09-1999 Allow the paper to lie between the thumb and fingers on the palm of the hand and introduce it for about 13 mm into the cylinder, which should be held in the ot
37、her hand and inclined at an angle of about 45 to the horizontal. Slip the calcium carbonate into the cylinder smoothly and without jerking. Any tendency towards sticking may be overcome by gently tapping the bottom end of the chute with a finger. On no account shall the cylinder be knocked or jolted
38、, nor shall the calcium carbonate in the paper be squeezed during the filling of the cylinder. g) Fit the rubber bung into the cylinder without jolting. h) Gently place the cylinder in the dropping-box and secure it. j) Start the timing device. k) With the thumb and forefinger of one hand gently tak
39、e hold of the upper part of the cylinder and during one second lift it to the full extent of its travel. Avoid any undue impact against the upper stop so that no jar is given to the calcium carbonate. l) At the commencement of the next second, smartly release the cylinder by quickly and completely w
40、ithdrawing the thumb and forefinger. m) Continue the process of lifting and dropping until 50 counted drops are completed, the cylinder falling once every two seconds. Rotation through an arc of about 10 should be given during the lifting that precedes each drop, since this will help to impart a lev
41、el surface to the calcium carbonate for the final volume reading. n) Immediately the 50 drops are completed remove the cylinder from the dropping-box, raise it to eye level and note volume to the nearest 1 ml (V). Any further drop in level after standing should be ignored. 4 Calculation Apparent den
42、sity after compaction, grammes per millilitre = where V = volume occupied by the 40 g of sample. This result shall be expressed to two significant figures. 40 V - Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1967 BSI 09-19993 Appe
43、ndix Summary of results NOTE 1The standard deviation is a measure of variation. A useful property of the standard deviation is that 95 % of the results are likely to fall within the limits of 2 standard deviation. Thus the 95 % limits of error are represented by 2 standard deviation. NOTE 2The numer
44、ical values quoted in the above table are based on the volume in millilitres occupied by 40 g of the powder after being subjected to the standard procedure, and not on the bulk densities calculated from these volumes. For convenience the standard deviations have also been given as percentages of the
45、 means. NOTE 3Each sample of precipitated calcium carbonate was tested on three separate days by all eleven laboratories. The variation within these sets of three repeat results represents the extent to which the laboratories can reproduce their own results on each sample and is measured by the stan
46、dard deviation within laboratories, i.e., Item ii) of, the above table. NOTE 4Item iii) represents the expected reproducibility within laboratories of the mean of three repeat tests on separate days and is derived from Item ii) by dividing the latter by 3. This has been done in order to compare the
47、variation between laboratories i.e. Item iv) of the above table with the variation within laboratories. Both Item iii) and Item iv) are thus based on the means of three tests. It is seen from the above table that the bulkier the precipitated calcium carbonate the less reproducible are the results bo
48、th within and between laboratories. For all three samples, the variation between laboratories is considerably greater than the variation within laboratories. Sample ASample BSample C i) Mean result over all laboratories (See Note 2.) ii) Standard deviation within laboratories iii) Standard deviation
49、 of mean of three tests within laboratories iv) Standard deviation of mean of three tests between laboratories 118.3 1.21 1.03 % 0.70 0;6 % 6.5 = 5.5 % 73.3 0.10 = 0.55 % 0.23 0.3 % 1.71 = 2.3 % 49.0 0.25 = 0.45 % 60.13 = 0.3 % 1.04 = 2.1 % Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1460:1997 4 BSI 09-1999 All dimensions in mm Figure 1 Dropping box Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:01:56 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 14