When the oxygen content is analyzed and the oxygen content in the air reaches as high as 21%, samples can be easily polluted or disturbed because of proper handling, thus resulting in inaccuracy of analysis results. A main cause is improper operation of the oxygen detector. The following part summarizes several factors which might influence accuracy of detection.
Simplification and cleanness of the oxygen detector’s gas circuit commutator
The oxygen analysis requires effective eliminate of various pipelines on the gas circuit, which can prevent the dead corner of the pipelines from causing pollution to the sample air. Therefore, the gas circuit commutator should be simplified as much as possible, and the connection parts with small dead corners should be chosen. In order to avoid use of water sealing, oil sealing and wax sealing, and prevent escape of the dissolved oxygen from causing pollution, and the purification equipment which might deepen pollution should not be introduced to the oxygen detector’s inlet pipeline. On in this way can cleanness of the commutator and data accuracy be ensured.
Selection of the pipeline materials
If the pipeline materials and surface are coarse, it might easily influence changes of the oxygen content in the sample gas. Usually, the plastic pipes and rubber pipes are seldom used as connection pipelines. Nor are copper pipelines or stainless steel pipelines adopted. For the ultramicroanalysis (meaning ＜0.1 ppm), the stainless steel tube which has been polished must be adopted.
Leakage of the gas detector
Before the initial startup of the oxygen detector, the leakage should be strictly detected. The oxygen detector cannot obtain accurate data results only under the prerequisite of airtightness. Lack of airtightness in any connection point, welding point and valve will cause reverse osmosis of the oxygen in the air into the pipeline and the oxygen gas detector. Finally, the oxygen content measured might be higher than the actual value.
Pollution of the oxygen gas detector
When the oxygen gas detector is used again, we should confirm whether there is air leaked into when connecting the sampling pipeline and carefully dry the leaked-in air. Try to prevent the mass air entering the oxygen to be measured in the sensor to influence the detection data. In the purification process of the pipeline commutator, certain method should be adopted to shorten the purification duration. Usually, the high-voltage discharge and the small-volume blowing can be alternated for quick purification of the pipeline.
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