BS 2924-2-1992 Aqueous extracts of paper board and pulp - Determination of conductivity《纸、纸板和纸含水萃取物 第2部分 电导率测定》.pdf

1、BRITISH STANDARD BS2924-2: 1992 ISO6587:1992 Aqueous extracts of paper, board and pulp Part2: Determination of conductivityBS2924-2:1992 This British Standard, having been prepared under the directionof the Paper and PrintingStandards Policy Committee, was published underthe authority of the Standar

2、ds Board and comesintoeffect on 15July1992 BSI08-1999 First published as part of BS2924December1957 Second edition September1968 First published as BS2924-2 October1983 Second edition July1992 The following BSI references relate to the work on this standard: Committee reference PAM/11 Draft for comm

3、ent91/41083DC ISBN 0 580 21032 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Paper and Printing Standards Policy Committee (PAM/-) to Technical Committee PAM/11, upon which the following bodies were represented: British Fibreboard Pa

4、ckaging Association British Paper and Board Industry Federation (PIF) British Printing Industries Federation British Telecommunications plc Envelope Makers and Manufacturing Stationers Association Her Majestys Stationery Office Man-made Fibres Producers Committee Ministry of Defence Paper Sack Devel

5、opment Association Ltd. PIRA (The Research Association for the Paper and Board, Printing and Packaging Industries) Post Office Society of British Printing Ink Manufacturers University of Manchester Institute of Science and Technology Amendments issued since publication Amd. No. Date CommentsBS2924-2

6、:1992 BSI 08-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling and preparation of the sample 1 7 Procedure 2 8 Calculation and expression of results 2 9 Test report 3 Table 1 Cond

7、uctivity of potassium chloride standard solutions 1 List of references Inside back coverBS2924-2:1992 ii BSI 08-1999 National foreword This Part of BS2924 has been prepared under the direction of the Paper and Printing Standards Policy Committee. It is identical with ISO6587:1992 Paper, board and pu

8、lps Determination of conductivity of aqueous extracts, published by the International Organization for Standardization (ISO). This edition supersedes BS2924-2:1983, which is withdrawn. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standar

9、ds are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard ISO186:1985 BS3430:1986 Method for sampling to determine the average quality of paper

10、 and board (Identical) ISO287:1985 BS3433:1986 Method for determination of moisture content of paper and board by the oven-drying method (Identical) ISO638:1978 BS4502:1980 Method for determination of dry-matter content of pulps (Identical) ISO7213:1981 BS6269:1982 Method for sampling pulps for test

11、ing (Identical) IEC554-2:1977 BS5626 Cellulosic papers for electrical purposes Part2:1979 Methods of test (Identical) Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see co

12、pyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS2924-2:1992 BSI 08-1999 1 1 Scope This International Standard specifies a method for the determination of the conductivity of aqueous extracts of paper, board or pulp, th

13、ese extracts having been prepared by a hot or a cold method. The method is applicable to all kinds of paper, board and pulps, except for papers used for electrical purposes. For high purity papers used for electrical purposes, the method used should be that given in IEC554-2. 2 Normative references

14、The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard

15、 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO186:1985, Paper and board Sampling to determine average quality. ISO287:1985, Paper and board

16、 Determination of moisture content Oven-drying method. ISO638:1978, Pulps Determination of dry matter content. ISO7213:1981, Pulps Sampling for testing. IEC554-2:1977, Specification for cellulosic papers for electrical purposes Part2: Methods of test. 3 Principle A2g sample is extracted for1h with10

17、0ml of boiling or cold, distilled or deionized water. Measurement of the conductivity of the extract at25 C by means of a conductivity meter or resistance bridge, using alternating current. 4 Reagents 4.1 Distilled or deionized water Distilled or deionized water shall be used throughout the test. Th

18、e conductivity of the water shall not exceed0,2mS/m after boiling and cooling as specified in7.2.2 (see note2). NOTE 1Usually, both distillation and deionization are required. Unless great care is exercised when distilling, and with the materials employed in the condenser and subsequent surfaces wit

19、h which the condensed vapour would possibly come in contact, the distillate can fail to reach the required level of conductivity. NOTE 2When it is not possible to obtain water of the specified purity, water with a higher conductivity may be used, but the conductivity of the water used should be stat

20、ed in the test report. 4.2 Potassium chloride, standard solutions. Use potassium chloride (KCl) of recognized analytical reagent grade, powdered, or fine crystals. Dry for2h at105 C 2 C and immediately prepare the following two solutions. 4.2.1 0,01 mol/l solution Dissolve0,7455g of the potassium ch

21、loride in water having a conductivity not greater than0,2mS/m, and dilute to1000ml. 4.2.2 0,001mol/l solution Dilute100ml of the0,01mol/l solution(4.2.1) to1000ml. Store the solutions in waxed glass bottles with ground glass stoppers. The conductivity values, in millisiemens per metre, of the two so

22、lutions are given in Table 1. Table 1 Conductivity of potassium chloridestandard solutions 5 Apparatus Ordinary laboratory apparatus, and 5.1 Flasks of chemically resistant glass, with ground glass joints, stoppers and efficient water-cooled reflux condensers made of the same quality of glass. All g

23、lassware shall be carefully rinsed with boiling distilled or deionized water(4.1). 5.2 Electric heater, adjustable at least to200W. 5.3 Conductivity meter or resistance bridge, with measuring cells provided with black platinum electrodes of area approximately1cm 2 , and capable of indicating the con

24、ductance of an aqueous extract with an error of less than 5% in the frequency range of50Hz to3000Hz. 5.4 Constant-temperature bath, capable of maintaining a temperature of25 C 0,5 C. 6 Sampling and preparation of the sample 6.1 Sampling Sampling of paper or board shall be carried out in accordance w

25、ith ISO186. Sampling of pulp shall be carried out in accordance with ISO7213. Concentration mol/l Temperature C Conductivity mS/m 0,01 18 20 25 122,05 127,80 140,88 0,001 25 14,693BS2924-2:1992 2 BSI 08-1999 6.2 Preparation of sample Cut or tear the sample into pieces approximately5mm 5mm in size fr

26、om portions that have not been touched by bare hands. Mix the pieces thoroughly. The sample shall not be touched at any time with bare hands. Clean protective gloves shall be worn at all times to protect the sample and the pieces prepared from it. Store the prepared samples in clean, covered contain

27、ers. 6.3 Determination of dry matter content Determine the dry matter content in accordance with ISO287 for paper or board and ISO638 for pulp. 7 Procedure 7.1 Determination of cell constant Wash the measuring cell (see5.3) several times with water(4.1), and then at least twice with thepotassium chl

28、oride standard solution(4.2.1 or4.2.2) the conductivity of which is nearest to that of the extract being measured. Measure the conductance or resistance of the cell, by means of the conductivity meter or resistance bridge(5.3), with a fresh portion of the same potassium chloride standard solution. C

29、alculate the cell constant using the appropriate formula or NOTE 3The conductance G (in siemens) is equal to1/R, where R is the resistance (in ohms). 7.2 Preparation of the aqueous extract 7.2.1 Weighing of sample Weigh2g 0,002g (oven-dry basis) of the sample(6.2) into a flask of suitable size(5.1)

30、which has been carefully washed with boiling water(4.1). 7.2.2 Hot extraction method With the aid of a pipette, measure100ml of water(4.1) into a separate flask(5.1). Attach the reflux condenser (see5.1) and heat the water to almost boiling. Remove the condenser and add the water to the flask contai

31、ning the sample(7.2.1). Replace the reflux condenser then boil gently for1h on the electric heater(5.2). Cool rapidly, with the condenser still fitted, to about25 C. Let the fibres settle and then decant the extract. Prepare the extract in duplicate. Using the constant-temperature bath(5.4), adjust

32、the temperature of the extract to25 C 0,5 C, and maintain that temperature throughout the test. 7.2.3 Cold extraction method With the aid of a pipette, measure100ml of water(4.1) into the flask containing the sample(7.2.1). Seal the flask with a ground glass stopper and leave to stand at room temper

33、ature(20 C to25 C) for1h. Shake the flask at least once during this time. Decant the extract. Prepare the extract in duplicate. Using the constant-temperature bath(5.4), adjust the temperature of the extract to25 C 0,5 C, and maintain that temperature throughout the test. 7.3 Determination of conduc

34、tivity Rinse the measuring cell (see5.3) carefully, several times with the water(4.1), and then twice more with the extract. Measure the conductance or resistance with fresh portions of the extract until a constant value is obtained. Repeat the determination with the duplicate extract. 7.4 Blank tes

35、t Carry out a blank test following the same procedure as for the determination, but omitting the sample. 8 Calculation and expression of results 8.1 If the meter gives conductance The conductivity, , of the extract is given, in millisiemens per metre, by the formula where G KCl is the conductance, i

36、n millisiemens, of the potassium chloride standard solution; R KCl is the resistance, in ohms, of the potassium chloride standard solution; KCl is the conductivity, in millisiemens per metre, of the potassium chloride standard solution (see Table 1). where J is the cell constant, determined as speci

37、fied in7.1; G x is the conductance, in millisiemens, of the extract; G o is the conductance, in millisiemens, corresponding to the blank test.BS2924-2:1992 BSI 08-1999 3 8.2 If the meter gives resistance The conductivity, , of the extract is given, in millisiemens per metre, by the formula 8.3 Expre

38、ssion of results Report the conductivity of the extract, in millisiemens per metre, as the mean of two determinations to the nearest1mS/m. The individual results should not differ by more than10% or2mS/m, whichever is the greater; if they do, repeat the determination on two additional extracts and r

39、eport the mean and range of all measurements. 9 Test report The test report shall include the following particulars: a) all the information necessary for complete identification of the sample; b) reference to this International Standard; c) the extract procedure used, i.e.hot or cold; d) the results

40、 expressed in millisiemens permetre; e) the conductivity of the water used, where this is greater than0,2mS/m; f) any unusual features observed in the course of the test; g) any operations not specified in this International Standard or in the International Standards to which reference is made, or a

41、re regarded as optional which might have affected the results. where J is the cell constant, determined as specified in7.1; R x is the resistance, in ohms, of the extract; R o is the resistance, in ohms, corresponding to the blank test.4 blankBS2924-2:1992 BSI 08-1999 List of references See national

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