Interpretation of the root cause of factors affecting the determination of oxygen sensors

When analyzing the oxygen content, especially the analysis of the trace oxygen, since the oxygen content in the air is as high as 21% O2, if it is not handled properly, it will easily cause sample contamination and interference, and the analysis result data will be incorrect. The main reason is that the oxygen sensor is mishandled.

Here are some factors that affect the measurement:

1. Simplification and cleanliness of the gas path system of the oxygen detector. Microanalysis requires that all types of pipe fittings in the gas path, beveling machine valves, meter heads, etc. blind spots on the sample gas must be effectively eliminated. Therefore, the manual bender should simplify the air circuit system as much as possible and choose connectors with small blind spots. And avoid using water seals, sealsts of oil and wax seals to prevent dissolved oxygen from escaping and causing pollution. It is also necessary to avoid adding purification equipment that is easy to pollute on the pipe leading from the sample gas to the inlet of the oxygen analyzer. This is the only way to ensure that the system is clean and the resulting data is correct.

2. Oxygen sensor pollution. 
 When reusing the oxygen detector, you should first check whether there is an air leak when connecting the sampling line, and you should carefully blow out the leak. air and try not to let a large amount of oxygen pass through the sensor to prolong the life of the sensor. In the process of purifying the pipeline system, in order to shorten the purification time, some methods are necessary. Generally, the riveting machine alternatively uses high degassinge pressure and low flow rate blowing to quickly purify the pipe.

3. Selection of pipe material.
Pipe material and surface roughness will also affect the change in oxygen content in the sample gas. It is generally not suitable to use plastic pipes, rubber pipes, etc. as connecting pipes. Copper or stainless steel tubing is typically used, and polished stainless steel tubing should be used for ultra-trace analysis (refers to <0.1 ppm).

4. Oxygen sensor leak.
The oxygen detector must undergo a rigorous leak test before its first use. Oxygen analyzers can only get correct data results under sealed and leak-free conditions. Any loose connection points, solder joints, valves, etc. will cause the infiltration of oxygen from the air into the pipeline and inside the analysisur of oxygen, which will result in high oxygen content.

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