The principle of trace oxygen analyzer mainly includes chemical cell method, primary cell method, fuel cell method, Hertz cell method and concentration cell method. When performing trace oxygen analysis, since the oxygen content in the air is as high as 21%, it is easy to cause contamination and disturbance to the sample if it is not handled properly, and the analysis result data is abnormal. The following are all aspects that need to be paid attention to during the test.
1. Leak
It is necessary to rigorously check for leaks before the initial use. The instrument can obtain accurate data results only under the premise of close and tightness. Any inconsistencies in joints, solder joints, valves, etc. will cause the oxygen in the air to reversely penetrate into the pipeline and the inside of the instrument, and then the result will be high oxygen content.
2. Pollution
When reusing the instrument, it is important to pay attention to whether air leaks when connecting the sampling pipeline. And it is necessary to carefully blow the leaked air clean, try not to let a lot of oxygen through the sensor to extend the life of the sensor. In the pipeline system purification process, in order to shorten the purification time, a certain method is required. Generally, high-pressure venting and small flow blowing and replacement are used to quickly purify the pipeline.
3. Simplification and cleanliness of the gas path system
Micro-analysis requires that it is necessary to effectively remove the pollution of the sample gas caused by various pipe fittings, valves, meters, etc. in the gas path. Therefore, the gas circuit system should be simplified as much as possible, and connectors with small dead angles should be selected. In addition, avoid the use of water seals, oil seals, and wax seals to prevent dissolved oxygen from escaping and causing pollution. It is also necessary to avoid adding pollution-prone purification equipment to the pipeline from the sample gas to the instrument inlet. Only in this way can we ensure that the system is clean and the data obtained is accurate.
4. Disturbance of background atmosphere
Like a fuel cell analyzer, different main background gases (related to the molar mass of the background gas) will affect the analysis results. And a small amount of hydrogen will have a greater impact on the analysis results.
5. Selection of pipe materials
The raw material and surface roughness of the pipe will also affect the change of oxygen content in the sample gas. Generally, plastic pipes, rubber pipes, etc. are not suitable for connecting pipelines. Generally, copper or stainless steel tubes are used. For ultra-micro analysis (refer to <0.1×10-4%), polished stainless steel tubes are necessary.
6. The influence of disturbing impurities
Disturbing impurities mainly refer to a small amount of unknown impurities in addition to the background gas and the components to be measured. For example, the fuel cell micro-oxygen meter is sensitive to acidic and oxidizing gases. If the gas contains acidic gas components, such as CO2, H2S, HCl, HCN Etc., the fuel pool sensor is prone to poisoning and failure.
The instrument is suitable for the following fields:
1. Air separation oxygen production, air separation nitrogen production, automatic analysis of oxygen content in chemical processes.
2. Analysis of oxygen content in protective gases in the electronics industry.
3. Analysis of oxygen content in protective gas of high-temperature sintering furnace such as magnetic materials.
4. Analysis of oxygen content in glass and building materials industries and analysis of oxygen content in various industries.
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