Precautions for Standard Gas in Sampling

Notes on standard gas injection:

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

1. The choice of sampling pipeline, because the rubber hose is very convenient to use, many traditional sampling pipelines use this type, but as we all know, the rubber hose has very strong adsorption to most organic gases and sulfur-containing gases, and its permeability The performance is also very strong, so it is not advisable to use various types of hoses for sampling, which will cause great deviations in the analysis data. It is recommended to use copper tubes, stainless steel tubes, and tetrafluoro tubes according to different gas properties, and use quartz-coated stainless steel tubes for sulfur-containing standard gas and sample gas.

2. For the replacement of sample gas, since the standard gas can only be sampled after passing through the pressure reducer and pipeline, the pressure reducer and pipeline must be fully replaced for accurate sampling. This replacement is not a simple purge. Because the dead volume of the pressure reducer is large, the cylinder valve should be opened and closed repeatedly for more than 3 times, every time the gas in the pressure reducer is exhausted, and then the system can be purged to correctly sample.

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

4. It is not advisable to try to take the standard gas from the standard gas cylinder into a sampling bag or other container, and then sample and analyze from the container, which will cause secondary pollution. So that the data of the sample gas can not be truly displayed.