Question 16Steam Plants - Assistant Engineer

The correct answer is A) prevent any air from contaminating the gas sample. When testing boiler flue gas using a chemical absorption apparatus, it is crucial to prevent any air from contaminating the gas sample. Air contamination can skew the results and lead to inaccurate measurements of the gas composition. To obtain accurate results, the gas sample must be isolated from any outside air and analyzed in a controlled environment. The other answer choices are not directly relevant to ensuring accurate results in this specific test scenario. Analyzing for nitrogen content before oxygen content, running each analysis for at least 3 minutes, or purging the apparatus with air before use may be important in other contexts, but they do not address the primary issue of preventing air contamination of the gas sample.