1、BRITISH STANDARD BS3908-9: 1991 Methods for The sampling and analysis of lead and lead alloys Part9: Sulphur in lead and lead alloysBS3908-9:1991 This British Standard, having been prepared under the directionof the Non-ferrous Metals Standards Policy Committee, was published underthe authority of t
2、he Standards Board and comes intoeffect on 30April1991 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference NFM/22 Draft for comment89/47213 DC ISBN 0 580 19375 6 Committees responsible for this British Standard The preparation of this British Standard wa
3、s entrusted by the Non-ferrous Metals Standards Policy Committee (NFM/-) to Technical Committee NFM/22, upon which the following bodies were represented: British Cable Makers Confederation Department of Trade and Industry (Minerals and Metals Division) Institute of Plumbing Institute of Roofing Inst
4、itution of Corrosion Science and Technology Lead Contractors Association Lead Development Association Lead Sheet Association Process Plant Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Ministry of Defence Society of British
5、Battery Manufacturers Amendments issued since publication Amd. No. Date CommentsBS3908-9:1991 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Calculation and expression of results 3 8 Pr
6、ecision 3 9 Test report 3 Figure 1 Apparatus for the determination of sulphur 2 Table 1 Repeatability and reproducibility values 3 Publication(s) referred to Inside back coverBS3908-9:1991 ii BSI 11-1999 Foreword BS3908 has been prepared under the direction of the Non-ferrous Metals Standards Policy
7、 Committee. It describes methods for the sampling and analysis of lead and lead alloys, each method being published as a separate Part. This Part of BS3908 is one of a series of methods in BS3908, the others being as follows. Part1: Sampling of ingot lead, lead alloy ingots, sheet, pipe and cable sh
8、eathing alloys; Part2: Arsenic in lead and lead alloys (photometric method); Part3: Bismuth in lead and lead alloys (photometric method); Part4: Copper in lead and lead alloys (photometric method); Part5: Nickel in lead and lead alloys (photometric method); Part6: Tellurium in lead and lead alloys (
9、photometric method); Part10: Antimony in lead alloys (titrimetric method); Part11: Tin in lead and lead alloys (volumetric method); Part13: Antimony in lead and lead alloys (low contents) (photometricmethod); Part15: Iron in lead and lead alloys (photometric method). The analytical methods in BS3908
10、 will be found suitable for the grades of metals covered by BS334, BS801, BS1178 and BS3909 and while in some instances they may appear to be lengthy, it should be realized that they are intended as reference methods, to be used in cases of dispute. A British Standard does not purport to include all
11、 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 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii
12、, pages1 to4, an inside back cover 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 inside front cover.BS3908-9:1991 BSI 11-1999 1 1 Scope This Part of BS3908 describes a method for th
13、e determination of the amount of sulphur present in lead and lead alloys by titrimetry. It is applicable to sulphur contents in the range0.0001% to0.02% by mass. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle A sample of the lead, or
14、lead alloy, is reacted with atin(II) chloride-hydrobromic acid mixture. Thehydrogen sulphide evolved is absorbed in a sodium hydroxide-methanol mixture, which is then titrated with mercury (II) acetate using dithizone as indicator. WARNING. The use of this method requires the use of substances, such
15、 as hydrobromic acid and compounds of mercury and antimony, that may be injurious to health if adequate precautions are not taken. 3 Reagents 3.1 General. During the analysis, use only reagents of recognized analytical quality and only distilled, or boiled deionized, water. 3.2 Mercury (II) acetate
16、solution (1),0.1g/L. Dissolve0.100 0.001g of mercury (II) acetate Hg(CH 3 COO) 2in water. Transfer to a1000mL one-mark volumetric flask, dilute to the mark and mix. NOTE1mL of this solution is equivalent to0.01mg sulphur. 3.3 Mercury (II) acetate solution (2),0.02g/L. Transfer50mL of the mercury (II
17、) acetate solution(1)(3.2) to a250mL one-mark volumetric flask, dilute to the mark and mix. This solution should be prepared immediately before use. NOTE1mL of this solution is equivalent to0.002mg sulphur. 3.4 Antimony tribromide solution,40g/L. Dissolve4.0 0.1g of high purity antimony (III) oxide
18、(Sb 2 O 3 ) in hydrobromic acid, (density,1.46g/mL to1.49g/mL). Dilute to100mL with the hydrobromic acid and mix. 3.5 Sodium hydroxide-methanol mixture,10g/L. Dissolve10 0.1g of sodium hydroxide (NaOH) in water, dilute to500mL and mix. Make up to1000mL with methanol and mix. 3.6 Tin(II) chloride-hyd
19、robromic acid mixture,30g/L. Dissolve3.0 0.1g of tin(II) chloride (SnCl 2 .2H 2 O) in hydrobromic acid (density1.46g/mL to1.49g/mL). Dilute to100mL with the hydrobromic acid and mix. 3.7 Dithizone indicator solution,0.4g/L. Dissolve0.02 0.001g of dithizone in50mL of acetone and mix. 3.8 Hydrochloric
20、 acid, 1.18g/mL. 3.9 Cylinder of nitrogen, free of oxygen. 4 Apparatus 4.1 Sulphur determination apparatus, as illustrated in Figure 1. All tubing and stoppers are to be made of glass or polypropylene, not rubber. 4.2 Ordinary laboratory apparatus. All burettes, pipettes and one-mark volumetric flas
21、ks used in this method shall be to class A accuracy, as specified in BS846, BS1583 and BS1792 respectively. 5 Sampling Obtain a suitable test sample for the analytical procedure by one of the methods given in BS3908-1. 6 Procedure WARNING. Small quantities of arsine and stibine may be evolved during
22、 this procedure. In view of this danger, the assembly of the apparatus(4.1) and the analytical procedures should be carried out in a fume cupboard. 6.1 General Scrupulously clean all glassware in hydrochloric acid solution(3.8). Immediately before use rinse thoroughly with distilled water and dry. 6
23、.2 Determination Weigh to an accuracy of 0.01g the appropriate mass of the freshly prepared test sample, as follows: a) for sulphur contents up to and including0.005%(m/m), use1g of the test sample; or b) for sulphur contents over0.005%(m/m), use0.5g of the test sample. NOTE 1The surface should be r
24、emoved from the bulk test sample before rolling or filing it to obtain the sample for analysis, in order to avoid high results due to the possible contamination of the surface of the metal with sulphur compounds in the atmosphere. Transfer the weighed sample to the small dry test tube and assemble t
25、he apparatus shown in Figure 1. Turn on the supply of oxygen-free nitrogen(3.9) and flush out the apparatus for5min. Transfer30mL of the sodium hydroxide-methanol mixture(3.5) to the50mL measuring cylinder (seeFigure 1), and adjust the delivery tube so that it almost reaches the bottom of the cylind
26、er.BS3908-9:1991 2 BSI 11-1999 Remove the stopper from the separating funnel. Quickly add10drops of antimony tribromide solution(3.4) and15mL of the tin(II) chloride-hydrobromic acid mixture(3.6) and immediately replace the stopper, adjusting the flow of oxygen-free nitrogen to give a continuous str
27、eam of small bubbles at a rate of three to four bubblespersecond(10mL/min). Turn on the magnetic stirrer. NOTE 2The hydrogen sulphide formed is displaced from the apparatus by the nitrogen. If the nitrogen flow is insufficient, part of the hydrogen sulphide will remain behind. After the sample has c
28、ompletely dissolved, continue passing the oxygen-free nitrogen for a further30min. Figure 1 Apparatus for the determination of sulphurBS3908-9:1991 BSI 11-1999 3 Transfer the solution from the measuring cylinder to a dry100mL round-bottomed flask, washing the cylinder with not more than5mL of water.
29、 Add two to four small drops of dithizone indicator(3.7) until the solution turns pale yellow. Titrate with mercury(II) acetate solution (1)(3.2) for sulphur contents of0.0005% or more, or with mercury (II) acetate solution(2)(3.3) for sulphur contents of less than0.0005%, until the solution changes
30、 from pale yellow to pink. Record the volume of titrant used. 6.3 Reagent blank With each batch of analyses carry out a reagent blank determination by following the procedures given in6.1 and6.2, using the same titrant but omitting the test portions. Record the volume of titrant used. Deduct the vol
31、ume of titrant used in titrating the blank from that used in titrating the sample and calculate the percentage of sulphur in the sample. 7 Calculation and expression of results The sulphur content, expressed as a percentage by mass, is given by the formulae: a) if solution (1)(3.2) was used as titra
32、nt or b) if solution (2)(3.3) was used as titrant where V is the volume (in mL) of the titrant,(3.2) or(3.3), used to titrate the sample; V b is the volume (in mL) of the same titrant used to titrate the blank; m is the mass (in g) of sample taken. 8 Precision The method given in this Part of BS3908
33、 was subjected to an interlaboratory test programme involving six laboratories, using three samples covering the range0.0003%(m/m) to0.0054%(m/m) of sulphur. The results obtained were processed in accordance with appendix Z of BS5497-1:1987 and the repeatability and reproducibility values obtained a
34、re given in Table 1. Table 1 Repeatability and reproducibility values 9 Test report The test report shall include the following particulars: a) an identification of the sample; b) the reference of the method used, i.e.BS3908-9:1991; c) the results obtained; d) any unusual features noted during the d
35、etermination; e) any operation not included in this Part of this BS3908, or regarded as optional, which might have an influence on the results. V V b ()0.01 10m - V V b ()0.002 10m - Sulphur level Repeatability conditions s r r s R R % (m/m) 0.0003 0.0006 0.0054 % (m/m) 0.00006 0.00003 0.00021 % (m/
36、m) 0.00016 0.00009 0.00058 % (m/m) 0.00006 0.00004 0.00032 % (m/m) 0.00017 0.00011 0.00090 NOTE 1 s r is the estimated standard deviation of the repeatability value; r is the repeatability value; s R is the estimated standard deviation of the reproducibility value; R is the reproducibility value. NO
37、TE 2The difference between two single results found on identical test material by one analyst using the same apparatus within the shortest feasible time interval will exceed the repeatability value r on average not more than once in20 cases in the normal and correct operation of the method. Single r
38、esults on identical test material reported by two laboratories will differ by more than the reproducibility value R on average not more than once in20 cases in the normal and correct operation of the method.4 blankBS3908-9:1991 BSI 11-1999 Publication(s) referred to BS334, Specification for composit
39、ional limits of chemical lead 1) . BS801, Specification for composition of lead and lead alloy sheaths of electric cables 1) . BS846, Specification for burettes. BS1178, Specification for milled lead sheet for building purposes 1) . BS1583, Specification for one-mark pipettes. BS1792, Specification
40、for one-mark volumetric flasks. BS3908, Methods for the sampling and analysis of lead and lead alloys. BS3908-1, Sampling of ingot lead, lead alloy ingots, sheet, pipe and cable sheathing alloys 1) . BS3908-2, Arsenic in lead and lead alloys (photometric method) 1) . BS3908-3, Bismuth in lead and le
41、ad alloys (photometric method) 1) . BS3908-4, Copper in lead and lead alloys (photometric method) 1) . BS3908-5, Nickel in lead and lead alloys (photometric method) 1) . BS3908-6, Tellurium in lead and lead alloys (photometric method) 1) . BS3908-10, Antimony in lead alloys (titrimetric method) 1) .
42、 BS3908-11, Tin in lead and lead alloys (volumetric method) 1) . BS3908-13, Antimony in lead and lead alloys (low contents) (photometric method) 1) . BS3908-15, Iron in lead and lead alloys (photometric method) 1) . BS3909, Specification for ingot lead for radiation shielding 1) . BS5497, Precision
43、of test methods. BS5497-1, Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. 1) Referred to in the foreword only.BS3908-9: 1991 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national
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