《ISO-671-1982.pdf》由会员分享，可在线阅读，更多相关《ISO-671-1982.pdf（7页珍藏版）》请在三一文库上搜索。
1、International Standard 671 INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONWEX4AYHAPDAHAR OF rAHHJAUbiA nOClAHAAPTH3AUb%WORGANlSATlON INTERNATIONALE DE NORMALISATION Steel and cast iron - Determination of sulphur content - Combustion titrimetric method Aciers et fontes - Dosage du soufre - Mkthode tit
2、rimbtrique epr b) 0,5 * 0,001 g for presumed sulphur contents between 0,lO and 0,20 % (m/m); c) for sulphur contents greater than 0,20 % (m/m), calculate the mass of the test portion so that it contains at the most 1 000 pg of sulphur. To create the same con- ditions of combustion, add to the test p
3、ortion a comp- lementary quantity up to 1 g of pure iron (4.4). 7.3 Combustion and determination 7.3.1 Non-refractory steel and cast iron Bring the electric furnace (D) to the temperature necessary to obtain a minimum temperature of 1 420 OC inside the combus- tion tube (El. Open taps (F) and (K) an
4、d regulate the flow of oxygen (I,2 I/min). In the absorption vessel (MI, place suf- ficient absorbent solution (4.6) to raise the level of the liquid 80 mm above the holes in the bubbler tube (L) (see note I) and add 4 or 5 drops of the mixed indicator (4.8). Neutralize by means of the standard sodi
5、um borate solution (4.7) until the in- dicator changes colour (greyish-green colouration). Note the burette reading k , in millilitres. Shut off the current of oxygen by closing taps (F) and (I). Open the oxygen inlet device (G), and introduce the boat and filter-cartridge assembly containing the te
6、st portion well into the large section of the combustion tube (E). Close oxygen inlet device (G), and adjust the flow of oxygen to 1,2 I/min by open- ing inlet tap (F) first and, immediately afterwards, outlet tap (K). Allow the test portion to burn for a period of 3 min, then for a further 4 min du
7、ring which simultaneously titrate the absorbent solution by means of standard sodium borate solution (4.7) un- til a steady greyish-green colour of the indicator is obtained (see note 2). Note the burette reading V, in millilitres (see note 3). NOTES 1 The liquid height of 80 mm is valid for a flow
8、of oxygen of 1,2 I/min as specified in the procedure. Diameter of holes : approximately 0,05 mm Figure 4 - Bubbler tube with holes 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/20
9、07 19:45:31 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 671-1982 (El 2 3 min is the minimum period necessan/ to flush carbon dioxide from the system before commencing titration. 3 The final titration may also be performed by means of instruments (e.g. potentiometric
10、 titration). 7.3.2 Refractory steel and cast iron Since the combustion of these steels and cast irons is difficult to start, it is necessary to add a quantity of flux (4.5). Note that the dimensions of the boat and cartridge assembly are intended to burn a maximum mass of I,2 g of metal. 8 Expressio
11、n of results 8.1 Calculation formula The sulphur (S) content is given, as a percentage by mass, by the formula 0,000 10 x (V2 - V1) x 100 m = 0.010 x !V2 - v, m where (V2 - Vt) is the volume, in millilitres, of the sodium borate solution (4.7) used for the titration; m is the mass, in grams, of the
12、test portion; 0,000 10 is the equivalent, in grams of sulphur, of the sodium borate solution (4.7). 9 Test report The test report shall include the following particulars : a) the method used, by reference to this International Standard; b) the results, and the form in which they are expressed; c) an
13、y unusual features noted during the determination; d) any operation not specified in this International Stan- dard, or any optional operations which may have influenced the result. 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/27/2007 19:45:31 MDTNo reproduction or networking permitted without license from IHS -,-,-