Due to the particularity of standard gas, sampling has special requirements, and many users have large data deviations due to irregular sampling. Here I provide several aspects that should be paid attention to in sample sampling:

1. The replacement of sample gas. Since the standard gas can only be sampled after passing through the pressure-relief device and pipeline, the pressure-relief device and pipeline must be fully replaced for accurate sampling. Such replacement is not a simple purge. Due to the large dead volume of the pressure-relief device, the valve of the steel cylinder should be opened and closed repeatedly for more than 3 times, and the gas in the pressure-relief device should be drained out each time. Then the purge system can sample correctly.

2. Attempts to take standard gas from a standard gas cylinder into a sampling bag or other container and then to take samples from the container for analysis are least desirable, resulting in secondary contamination. So that the sample gas data can not be truly displayed.

3. The choice of sampling pipe, plastic because it is convenient to use, many have adopted such conventional injection pipeline, but it is well known that the hose for the majority of organic gases, and sour gas adsorption is very strong, and its permeability is strong, so the use of all kinds of rubber hose to sampling is not desirable, to analyze data caused great deviation. It is recommended to use copper tube, stainless steel tube, tetrafluoride tube according to different gas properties, and it is best to use stainless steel tube coated with quartz for standard gas and sample gas containing sulfur.

4. The air tightness of the injection pipeline and the leakage of the injection pipeline have a great impact on the accuracy of the sample data, but have a greater impact on the low concentration of oxygen. Therefore, the air tightness of the sampling line must be strictly checked.