1、rr 1421 ta om ceramic crucible amrd 1,OlaQ g1 to theatkr. Cowereach withi11.5g i Q,l g af the a- by ttre Same-uperator ampi note 11 UJinglthe-mapparcrtus, wcth ai new caiibrationy 3 Erom the. WJJ mlues obtainedl om day i1 the repeatzibiiity- (v amel repmducibility (Ri wem calculated using the prmedu
2、re specified in IS0 5725. Prom the finr value- abtaimd an day. 1 and. the. mtue oblained om day 2, the. wirirhnll Gasircrn JSS, 245-1 Catborn CTIF- FEI II Ca between days i ): Non-certified w1,alw.e Q x x c c C.M The gemaar is usually a 1,s UVA ta 2,s WA apparent meri unit, but tk frequency used by
3、cemin rnamufamnws ma+ te different. Valus of 2 MHz ta Ei MHZ; 75 Wz; amj 2D3 MHz. trave bem us txz coollkaediin axygen im alfixed volume a one-mark volumetric flasks with flanged rim, conical socket and conical joint Laboratory glassware; classes A and B one-mark bulb pipettes Laboratory glassware:
4、burettes: general requirements International Patent Classification F 27 D 23/00 G O1 N 33/20 EN comprises 9 pages. DIN EN 24 935 Eng/. Price group 8 Beuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). 03.93 Sales No. 11 08 EUROPEAN STANDARD NORME EUROPENNE E
5、UROPISCHE NORM EN 24 935 December 1991 UDC 669.1 : 669.14 : 620.1 : 543.422.4 : 546.22 Descriptors: Steel, cast iron, chemical analysis, determination of sulfur content, infrared spectroscopy, induction furnace. English version Steel and iron Determination of sulfur content Infrared absorption metho
6、d after combustion in an induction furnace (IS0 4935 : 1989) Aciers et fontes; dtermination du soufre; mthode par absorption dans linfrarouge aprs combustion dans un four induction (IS0 4935 : 1989) Stahl und Eisen; Bestimmung des Schwefelgehalts; Methode mit Infrarot- absorption nach Verbrennung im
7、 Induk- tionsofen (IS0 4935 : 1989) This European Standard was approved by GEN on 1991-12-20 and is identical to the IS0 Standard as referred to. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a
8、national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three oficial versions (English, French, German). A version in
9、 any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, I
10、celand, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Staccart 36, B-1050 Brussels O 1991. Copyright reserv
11、ed to all GEN members. Ref. No. EN 24 935 : 1991 E Page 2 EN 24 935 : 1991 Foreword On the proposal of Technical Committee TC 20, the Coordinating Commission (COCOR) of the European Committee for Iron and Steel Standardization (ECISS) decided in May 1991 to submit International Standard IS0 4935 : 1
12、989 to Formal Vote. This European Standard was approved by CEN on 1991 -12-20. In accordance with the CENKENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembou
13、rg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Steel and iron - Determination of sulfur content - Infrared absorption method after combustion in an induction furnace Endorsement notice The text of the International Standard IS0 4935 : 1989 was approved by CEN as a
14、European Standard without any modifi- cation. Page 3 EN 24 935 : 1991 Reference ,f sulfur standard solution 4.6.1 4.6.2 4.6.3 4.6.4 4.6.5 4.6.6 4.6.7 1 Scope This International Standard specifies an infrared absorption method after combustion in an induction furnace for the deter- mination of sulfur
15、 content in steel and iron. The method is applicable to sulfur contents between 0,002 % (rn/rn) and 0,lO % (mim) Mass of potassium Concentration sulfate of sulfur 9 mglrnl 0.217 4 09 0,380 4 0,70 0.543 4 1 .o0 1,086 9 2.00 1,902 2 3.50 2.717 2 5,00 4,347 5 8.00 4 Reagents and materials During the an
16、alysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At
17、the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encour- aged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and IS0
18、 maintain registers of currently valid International Standards. IS0 377 : 1985, Wrought steel - Selection and preparation of samples and test pieces. IS0 385-1 : 1984. Laboratory glassware - Burettes - Part I: General requirements. IS0 648 : 1977, Laboratoy glassware - One-mark pipettes. IS0 1042 :
19、1983, Laboratoryglassware - One-mark volumetric flasks. IS0 5725 : 1986, Precision of test methods - Determination of repeatability and reproducibiliy for a standard test method by inter-labpratory tests. 3 Principle Combustion of a test portion with accelerator at a high temperature in a high-frequ
20、ency induction furnace in a current of pure oxygen. Transformation of sulfur into sulfur dioxide. Measurement by infrared absorption of the sulfur dioxide carried by a current of oxygen. 4.1 An oxidation catalyst copper(ll) oxide or platinum1 tube heated to a temperature above 450 OC must be used pr
21、ior to a purify- ing unit (see annex Cl, when the presence of organic con- taminants is suspected in the oxygen. Oxygen, 99.5 % (rn/rn minimum. 4.2 Pure iron, of known low sulfur contents less than 0,ooO 5 % (mlrn. 4.3 dirty test samples, for example, acetone. Suitable solvent, appropriate for washi
22、ng greasy or 4.4 Magnesium perchlorate Mg(CIO,l, particle size : from 0,7 mm to 1.2 mm. 4.5 Accelerator, tungsten, free of sulfur, or of known sulfur contents less than 0,ooO 5 % (rnlm. The mesh size of the ac- celerator may be dependent on the type of apparatus used. 4.6 Sulfur, standard solutions.
23、 Weigh, to the nearest 0.1 mg, the mass described in table 1 of potassium sulfate minimum assay: 99,9 % rn/rn)l previously dried at 105 OC to 110 OC for 1 h or to constant mass and cooled in a desiccator. Table 1 Page 4 EN 24 935 : 1991 Transfer to seven 100 mi beakers and dissolve in water. Transfe
24、r quantitatively into seven 100 ml one-mark volumetric flasks. Dilute to the mark with water and mix. 4.7 Inert ceramic (attapulgus clay) impregnated with sodium hydroxide, particle size: from 0.7 mm to 1,2 mm. 5 Apparatus During the analysis, unless otherwise stated, use only ordinary laboratory ap
25、paratus. All volumetric glassware shall be class A, in accordarlce with IS0 385-1, IS0 648 or IS0 1042 as appropriate. The apparatus required for combustion in a high-frequency induction furnace and the subsequent infrared absorption measurement of the evolved sulfur dioxide may be obtained commerci
26、ally from a number of manufacturers. Follow the manufacturers instructions for the operation of the equipment. Features of commercial instruments are given in annex C. 5.1 less than 1 pl. Micropipettes, 50 pl and 100 HI, limit of error shall be 5.2 0,3 g in mass and approximately 0,4 ml in volume. T
27、in capsule, about 6 mm in diameter, 18 mm in height, 5.3 in an induction furnace. Ignite crucibles in an electric furnace in air or in a current of oxygen for not less than 2 h at 1 100 OC and store in a desic- cator before use. NOTE - For the determination of low sulfur contents it is advisable to
28、ignite crucibles at 1 350 OC in a current of oxygen. Ceramic crucible, capable of withstanding combustion 6 Sampling Sampling shall be carried out in accordance with IS0 377 or appropriate national standards for iron. 7 Procedure SAFETY INSTRUCTIONS - The risks related to combus- tion analysis are m
29、ainly bums in pre-igniting the ceramic crucibles and in the fusions. Use crucible tongs at all times and suitable containers for the used crucibles. Nor- mal precautions for handling oxygen cylinders shall be taken. Oxygen from the combustion process shall be removed effectively from the apparatus s
30、ince a high con- centration of oxygen in a confined space can present a fire hazard. 7.1 Apparatus conditioning Purify the oxygen supply using tubes packed with the inert ceramic (attapulgus clay) impregnated with sodium hydroxide (4.7) and magnesium perchlorate (4.4), and maintain a quies- cent flo
31、w rate whiist on standby. Maintain a glass wool filter or a stainless steel net as a dust collector. Clean and change as necessary. The furnace chamber, pedestal post and filter trap shall be cleaned frequently to remove oxide build-up. Allow each item of equipment to stabilize for the time recom- m
32、ended by the equipment manufacturers when the main supply is switched on after being out of action for any length of time. Aher cleaning the furnace chamber and/or changing filters or after the equipment has been inoperative for a period, stabilize the apparatus by burning several samples of similar
33、 type to the samples to be analysed prior to setting up for analysis. Flush oxygen through the apparatus and adjust the instrument controls to give a zero reading. If the instrument used provides a direct reading in percentage sulfur, adjust the instrument reading for each calibration range as follo
34、ws. Select the certified reference material with a sulfur content close to the maximum sulfur content in the calibration series, measure the sulfur content of the certified reference material in the same manner as specified in 7.4. Adjust the reading of the instrument to the certified value. NOTE -
35、This adjustment shall be made before the calibration as specified in 7.5. It cannot replace or correct the calibration. 7.2 Test portion Degrease the test sample by washing in a suitable solvent (4.3). Evaporate the last traces of the washing liquid by heating. Weigh, to the nearest 1 mg, 1 g of the
36、 test sample for sulfur contents less than 0,04 % (rn/rn) and 0,5 g for sulfur contents greater than O,4 % irn/mi. NOTE - The mass of the test portion may be dependent on the type of instrument used. 7.3 Blank test Prior to the determination, carry out the following blank tests in duplicate. Transfe
37、r a tin capsule (5.2) to a ceramic crucible (5.3). press the tin capsule lightly against the bottom of the crucible. Add the same quantity of the pure iron (4.2) as the test portion (7.2) and 1.5 g I 0,l g of the accelerator (4.5). Treat the crucible and contents as specified in the second and third
38、 paragraphs of 7.4. Obtain the readings of the blank tests and convert them to milligrams of sulfur by means of the calibration graph (7.5). The blank value is obtained by subtracting the mass of sulfur in the pure iron (4.2) used see note 1) from the mass of sulfur in the blank tests. The mean blan
39、k value (ml) is calculated from the two blank values see note 2). Page 5 EN 24 935 : 1991 NOTES 1 Determine the sulfur content in the pure iron (4.2) as follows. Prepare two ceramic crucibles (5.3). Transfer a tin capsule (5.21 to each and press the capsule lightly against the bottom of the crucible
40、. Add 0,500 g of the pure iron (4.2) to one ceramic crucible and 1 ,o00 g to the other. Cover each with 1,5 g f 0.1 g of the accelerator (4.5). Treat the crucible and contents as specified in the second and third paragraphs of 7.4. Convert the values obtained into milligrams of sulfur by means of th
41、e calibration graph (7.51. The mass m21 of sulfur with 0,500 g of pure iron added, is obtained by subtracting the value (m31 corresponding to 0.500 g of the pure iron from that m,l of 1,OJ g of pure iron. The mass im,) of sulfur of 1,O g of pure iron added is twice the mass (m,) of the sulfur with 0
42、.500 g of pure iron added : m5 = 2 x m2 = 2 x m, - m3) 2 The mean blank value shall not exceed 0,005 mg of sulfur and the difference between the two blank values shall not exceed 0,003 rng of sulfur. If this value is abnormally high, investigate and eliminate the source of contamination. 7.4 Determi
43、nation Transfer a tin capsule (5.2) to a ceramic crucible (5.31, press the tin capsule lightly against the bottom of the ceramic crucible, add the test portion (7.2) and cover with 1,5 g k 0,l g of the accelerator (4.5). Place the ceramic crucible and contents on the pedestal post, raise to the comb
44、ustion position and lock the system. Operate the furnace in accordance with the manufacturers instruc- tions. At the end of the combustion and measuring cycle, remove and discard the crucible, and record the analyser reading. 7.5 Establishment of the calibration graph 7.5.1 Samples having sulfur con
45、tents less than 0,005 % (m/m) 7.5.1.1 Using the 50 pI micropipette (5.11, transfer water (zero member and sulfur standard solutions (4.6) as indicated in table 2 to four separate tin capsules (5.2). Evaporate slowly at 90 OC until completely dry and then cool to room temperature in a desiccator. Pre
46、paration of the calibration series Table 2 Water 4.6.1 4.6.2 4.6.3 O 20 35 50 0,Ooo o 0.002 o 0,003 5 0,005 o 7.5.1.2 Measurements Transfer the tin capsule from 7.5.1.1 to a ceramic crucible (5.31, press the tin capsule lightly against the bottom of the ceramic crucible, add 1,ooO g of the pure iron
47、 (4.2) and cover with 1.5 g t 0,l g of the accelerator (4.5). Treat the crucible and contents as specified in the second and third paragraphs of 7.4. 7.5.1.3 Plotting the calibration graph The net reading is obtained by subtracting the reading of the zero member from that of each member of the calib
48、ration seriw. Prepare a calibration graph by plotting the net reading against milligrams of sulfur for each member of the calibration series. 7.5.2 Samples having sulfur contents between 0,005 % (m/ml and O,4 % mlml 7.5.2.1 Preparation of the calibration series Using the 50 pl micropipette (5.11, tr
49、ansfer water (zero member and sulfur standard solutions (4.6) as indicated in table 3 to five separate tin capsules (5.2). Evaporate slowly at 90 OC until completely dry and then cool to room temperature in a desiccator. Table 3 Reference of sulfur standard solution Water 4.6.3 4.6.4 4.6.6 4.6.7 Mass of sulfur 1.i9 O 50 100 250 400 Sulfur content in the test portion YO mlrn) 0,Ooo o 0,005 O 0,010 o 0,025 O 0,040 o 7.5.2.2 Measurements As specified in 7.5.1.2. 7.5.2.3 Plotting the calibration graph As specified in 7.5.1.3. 7.5.3 Samples having sulf
