BS 1460-1967 Method for determination of apparent density after compaction of precipitated calcium carbonate《沉淀碳酸钙压缩后的外观密度测定方法》.pdf

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1、BRITISH STANDARD BS1460:1967 Incorporating Amendment No.1 Method for Determination of apparent density after compaction of precipitated calcium carbonateBS1460:1967 This British Standard, havingbeen approved by theChemicals Industry StandardsCommittee and endorsed by the Chairman of theChemicals Div

2、isional Council,was published under theauthorityof the General Councilon 18 January 1967 BSI 09-1999 First published December 1948 First revision January 1967 The following BSI references relate to the work on this standard: Committee reference CIC/9 Draft for comment 66/1471 ISBN 0 580 35530 9 Co-o

3、perating organizations The Chemicals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives of the following Government departments and scientific and industrial organizations: Board of Trade British Iron and Steel Federation Chemical In

4、dustries Association* Fertilizer Manufacturers Association Gas Council Institute of Vitreous Enamellers Institution of Gas Engineers Ministry of Defence, Army Department Ministry of Health National Sulphuric Acid Association Royal Institute of Public Health and Hygiene The industrial organization ma

5、rked 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 Laboratory Ware Association British Paper and Board Makers Association (Incorporated) British Polish Manufacturers Associat

6、ion British Waterworks Association London Chamber of Commerce (Incorporated) Proprietary Association of Great Britain Toilet Preparations Federation Welwyn Hall Research Association Amendments issued since publication Amd. No. Date of issue Comments 6199 July 1967 Indicated by a sideline in the marg

7、inBS1460:1967 BSI 09-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Apparatus 1 3 Procedure 1 4 Calculation 2 Appendix Summary of results 3 Figure 1 Dropping box 4 Figure 2 Apparatus (assembled) 5 Figure 3 Cylinder 6BS1460:1967 ii BSI 09-1999 Foreword This

8、 standard makes reference to the following British Standards: BS410, Test sieves. BS903, Methods of testing vulcanized rubber Part A7: Determination of hardness. This British Standard was first issued in1948, (under the authority of the Fine Chemicals Industry Standards Committee, now incorporated i

9、nto the Chemicals Industry Standards Committee), when it was developed from a test which had been in industrial use for many years 1) . The method consists of ascertaining the bulk of a known mass of a prepared sample of precipitated calcium carbonate after compaction by a standardized procedure. Fo

10、llowing 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 expected for differen

11、t grades of precipitated calcium carbonate. In making these tests three grades of precipitated calcium carbonate, having apparent densities after compaction (g/ml) about0.30 (Sample A),0.50 (SampleB), and0.80(SampleC), were used. The results of the statistical analysis of the data obtained are set o

12、ut 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 regard to the known difficulti

13、es 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 SampleA. This was due to the fact that some feature of the test (probablyassociated with the transfer of the sampl

14、e 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 method would serve a useful pu

15、rpose 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 apparatus, in particular o

16、f 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 precision than is usual in su

17、ch 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 apparatus faithfully copie

18、s 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.BS1460:1967 BSI 09-1999 iii A British Standard does not purport to include all the necessary pr

19、ovisions 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 a front cover, an inside front cover, pagesi toiv, pages1to6 and a

20、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 inside front cover.iv blankBS1460:1967 BSI 09-1999 1 1 Scope This British Standard describes a method for the determination of apparent densi

21、ty 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 it is necessary to assess the details of the test in rel

22、ation 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 reproducibility at the expense of discrimination, and cons

23、ideration 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 test results are reported on such a modified test they sh

24、ould be accompanied by a statement in the form: “Tested generally in accordance with BS1460, but using X g of sample and Y drops”. 2 Apparatus 2) The apparatus required, the special parts of which are depicted diagrammatically in Figure 1, Figure 2 and Figure 3 comprises: a) Cylinder, glass with a s

25、olid base ground flat at right angles to the axis of the cylinder. It shall be graduated by2ml subdivisions over the range20ml to250ml. The graduations shall be permanently numbered at10ml intervals. The maximum permissible error in the graduations at any point shall be 0.6ml provided that the diffe

26、rence between error at any two points does not exceed0.6ml. The internal depth from the250ml graduation mark to the base shall be220mm to240mm. The empty cylinder together with its rubber bung, shall weigh250 5g. b) Dropping box, secured to a rigid bench or table. The distance between the flat groun

27、d base of the cylinder and the rubber base pad, when the cylinder is raised to the full height, shall be251mm, i.e.the total lift of the cylinder shall be corrected to25 1mm by suitable adjustment of the shelf. The rubber base pad shall have a nominal thickness of56mm and a hardness of70 85I.R.H.D.

28、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 least100mm in diameter. It is necessary that the pointer should show a significant deflectio

29、n for a change in load of0.25g. e) Sampling paper, black glazed. f) Finger stalls, smooth rubber. g) Sieve 4) , nominal aperture width500microns, known as mesh number30. 3 Procedure a) Weigh out approximately42g of a fresh portion of the material on a piece of paper. b) Fold a piece of blank glazed

30、sampling paper250 250mm with two parallel creases to form a channel13mm 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 by other suitable means. c) Place the sieve on the prepared paper on the bench, in such a manner

31、 that there is a50mm 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 the calcium carbonate through the sieve, using a short stroke. If the sieve tends to clog, raise i

32、t about25mm 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 to40 0.25g. f) Pick up the paper with the sieved sample and form it into a chute. 2) The special parts of the apparatus are

33、available commercially from Messrs. Jencons (Scientific) Limited, Hemel Hempstead, England. 3) BS903, “Methods of testing vulcanized rubber” Part A7: “Determination of hardness”. 4) BS410, “Test sieves”.BS1460:1967 2 BSI 09-1999 Allow the paper to lie between the thumb and fingers on the palm of the

34、 hand and introduce it for about13mm into the cylinder, which should be held in the other hand and inclined at an angle of about45 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

35、end of the chute with a finger. On no account shall the cylinder be knocked or jolted, 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

36、. j) Start the timing device. k) With the thumb and forefinger of one hand gently take 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 comm

37、encement of the next second, smartly release the cylinder by quickly and completely withdrawing the thumb and forefinger. m) Continue the process of lifting and dropping until50counted drops are completed, the cylinder falling once every two seconds. Rotation through an arc of about10 should be give

38、n during the lifting that precedes each drop, since this will help to impart a level surface to the calcium carbonate for the final volume reading. n) Immediately the50drops are completed remove the cylinder from the dropping-box, raise it to eye level and note volume to the nearest1ml (V). Any furt

39、her drop in level after standing should be ignored. 4 Calculation Apparent density after compaction, grammes per millilitre = where V = volume occupied by the40g of sample. This result shall be expressed to two significant figures. 40 V -BS1460:1967 BSI 09-1999 3 AppendixSummary of results NOTE 1The

40、 standard deviation is a measure of variation. A useful property of the standard deviation is that95% of the results are likely to fall within the limits of 2 standard deviation. Thus the95% limits of error are represented by 2 standard deviation. NOTE 2The numerical values quoted in the above table

41、 are based on the volume in millilitres occupied by40g 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 means. NOTE 3Each sample of precipitat

42、ed 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 standard deviation within laboratories, i.e

43、., Itemii) of, the above table. NOTE 4Itemiii) represents the expected reproducibility within laboratories of the mean of three repeat tests on separate days and is derived from Itemii) by dividing the latter by 3. This has been done in order to compare the variation between laboratories i.e.Itemiv)

44、 of the above table with the variation within laboratories. Both Itemiii) and Itemiv) 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 both within and between laboratories. For all th

45、ree samples, the variation between laboratories is considerably greater than the variation within laboratories. Sample A Sample B Sample C i) Mean result over all laboratories (See Note2.) ii) Standard deviation within laboratories iii) Standard deviation of mean of three tests within laboratories i

46、v) 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%BS 1460:1997 4 BSI 09-1999 All dimensions in mm Figure 1 Dropping boxBS1460:1967 BSI 09-1999 5 Figure 2 Apparatus (assembled)B

47、S1460:1967 6 BSI 09-1999 Figure 3 CylinderblankBS1460:1967 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is inc

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