To ensure the accuracy and stability of the test data and the correctness and effectiveness of the entire measurement process during the daily operation of the carbon-sulfur analyzer, real-time monitoring of fluctuations in the test data during routine detection is required. A daily monitoring method for the entire measurement process of the carbon-sulfur analyzer can be adopted based on the measurement uncertainty and using control charts.
Since all factors affecting the detection process—including the testing environment, detection method, operator, and other conditions for carbon and sulfur—remain identical during the analysis, this paper only describes the control method for sulfur.
Uncertainty refers to the degree to which the measured value cannot be determined, mainly caused by the existence of measurement errors, and also indicates the reliability of the result. The smaller the uncertainty, the closer the result is to the true value of the measurand, the higher the quality, the higher the level, and the higher its application value. An effective evaluation method of uncertainty can also provide data reference and lay a theoretical foundation for the daily monitoring of the infrared carbon-sulfur analyzer.
2.1 Measurement Standard
In accordance with the relevant operating instructions, instrument manuals and corresponding operational specifications.
2.2 Environmental Conditions
Temperature: (20 ± 5) ℃; Relative humidity ≤ 60%.
2.3 Testing Equipment
Infrared carbon-sulfur analyzer, whose performance shall meet the requirements of **JJG 395-2016 *Verification Regulation for Carbon and Sulfur Determination Analyzers.
2.4 Measurand
Sulfur content in the sample.
2.5 Measurement Procedure
Turn on the carbon-sulfur analyzer in accordance with the operating instructions. After the analyzer has stabilized for approximately 2 hours, check the system monitoring program and perform the gas leakage test to ensure the instrument is in a stable condition. Place the sample into the high-frequency furnace of the infrared carbon-sulfur analyzer for combustion. After absorption by the instrument, the elemental content in the sample is analyzed and determined.
2.6 Application of Evaluation Results
Under the above conditions, the measurement results can generally directly use the evaluation results of this uncertainty.
2.7 Mathematical Model
y＝x+Δy
Where:
- (y) — percentage content of sulfur;
- (x) — reading value of the infrared carbon-sulfur analyzer;
- (Δy) — influence of the uncertainty of the infrared carbon-sulfur analyzer.
