Due to the particularity of standard gases, there are special requirements for sampling. Many users have significant data deviations due to non-standard sampling. Here, I provide several aspects that should be noted when sampling samples: 

1、 The replacement of sample gas, as standard gas can only be sampled after passing through a pressure reducer and pipeline, accurate sampling requires sufficient replacement of the pressure reducer and pipeline. This replacement is not simply a simple blow. Because the dead volume of the pressure reducer is large, the steel cylinder valve should be opened and closed repeatedly for more than 3 times. Each time, the gas in the pressure reducer should be discharged, and then the system should be blown to sample correctly

2、 Attempting to take the standard gas from a standard gas cylinder into a sampling bag or other container, and then sample and analyze it from the container, is the least advisable, as it causes secondary pollution and makes the data of the sample gas unable to be accurately represented

3、 The selection of sampling pipelines, due to the convenience of using rubber hoses, many traditional injection pipelines use this type. However, it is well known that rubber hoses have strong adsorption for most organic gases and sulfur-containing gases, and their permeability is also strong. Therefore, using various types of rubber hoses for sampling is not advisable, which causes significant deviation in the analysis data. It is recommended to use copper tubes, stainless steel tubes, and PTFE tubes according to different gas properties. For sulfur-containing standard gases and sample gases, it is best to use stainless steel tubes coated with quartz inside

4、 The airtightness of the sampling pipeline and the leakage of the sampling pipeline have a significant impact on the accuracy of the sample data, with a greater impact on low concentration oxygen. Therefore, it is necessary to strictly check the airtightness of the sampling pipeline

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