When testing the sulfur content in iron and steel with carbon-sulfur element analyzer by burning, the sulfur can not completely be transformed as sulfur dioxide, and the conversion rate is related to the experiment condition, the sulfur content in the sample can not be calculated directly with the academic value according to standard solution concentration. Therefore, the standard sample has to be used under the identical condition of the test sample to work out the sulfur titer and then work out the sulfur content in the test sample, thus the selection of the standard sample with sulfur shows gravely important.

 

When testing the sulfur with the carbon-sulfur analyzer by burning method, the weight-hour method, reduction-colorimetric method as well as the original potentiometric titration method will be selected to determine the value, and standard sample with similar mark number and similar content will be adopted to work out the titer and then work out the sulfur content.

 

The test results of carbon steel or pig iron stand sample which have been preserved for a very long time (such as those over 10 years) may turn out severe deviation, therefore, they will be used only after re-determining the value. The standard sample after use will be covered and put back to the dryer container as to avoid the chances of the carbon dioxide, sulfur dioxide, didrogen oxide in the air being attached to its surface from its exposure and influence the its standard value.

 

When testing the sample of sulfur content less than 0.010%, as introduced in GB223.2-1981, adopt 0.1000g standard sample with sulfur content over 0.10% and 0.9000g standard sample with sulfur content less than 0.001% and mix them to undertake the calibration. The blank value shall include those produced by porcelain boat, porcelain cover, fluxing agent as well as 0.9g standard sample with sulfur content less than 0.001 and etc. The sample will be in weight of 1.000g.