How is the purity of liquid oxygen and liquid nitrogen in air separation units analyzed?

A micro-oxygen analyzer is used for liquid nitrogen, while a high-purity oxygen analyzer is used for liquid oxygen.

Thank you very much. I also prepare the instrument list in the same way, hehe. I wasn’t sure if it’s actually used that way as well, but now I’m confident: lol

For the analysis of high-purity gases, you can ask the moderator huapiaoxu521. I suggest that for determining the purity of liquid oxygen and liquid nitrogen, impurity analysis should be the preferred method, with the purity of the sample being determined through subtraction. In liquid oxygen analysis, the analysis of total hydrocarbons is a very important testing parameter; it is crucial for safety during the storage and transportation of liquid oxygen, as well as in its distillation process, and therefore cannot be ignored.

Could you please tell me what methods and instruments are used for total hydrocarbon analysis? Thank you. Hurry up and apply to add the moderator as a friend, hehe:P

This post was last edited by huapiaoxu521 on 2015-9-15 12:37. First of all, I would like to thank senior @qugd; having listened to your teachings many years ago, I am now able to help others, and that is also thanks to you. Thank you. There are two most important tests in air separation units, which are essential items to be analyzed; they are also referred to as air separation safety analysis. 1. Analysis of acetylene and nitrous oxide in liquid oxygen; nitrous oxide can cause acetylene to aggregate, and under normal conditions, the concentrations of acetylene and nitrous oxide should be below 1 ppm. 2. The analysis of total hydrocarbons in liquid oxygen is very important. The above two items are indicators that must be monitored for air separation safety. Another aspect is product analysis, namely the analysis of liquid oxygen and liquid nitrogen. The product quality standards of domestic air separation companies such as Hangyang and Chuan Kong, as well as foreign companies like Linde, Yingde, and Air Liquide, are generally at the 5N level (99.999%). Therefore, the method used for analyzing the content of these products is the subtraction method (chromatography), which involves determining the amount of impurities; typically, the concentration of impurities is around 1 ppm. The analysis methods are as follows: 1. The components to be analyzed in liquid oxygen are H2, N2, CH4, CO, CO2, C2H2, N2O, and C1-C4. (Generally, the C1-C4 content of total hydrocarbons is calculated.) 2. The components to be analyzed in liquid nitrogen are H2, O2+Ar, CH4, CO, and CO2; analysis can be carried out using a dual-detector chromatograph with DID+FID (helium discharge ionization + hydrogen flame) technology. Equipped with a deoxidation system, it is possible to analyze all impurities present in liquid oxygen and liquid nitrogen, as well as liquid argon, which is a by-product of air separation processes. I hope this helps. I work in the analysis of high-purity gases; feel free to contact me if you need any assistance. Thank you. AGC Company, Liu Guiqiang, 13911644071

Thank you very much. Two gas chromatographs have also been installed. The phone number is saved. There’s still so much I need to learn:* dizzy:

I learned it! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !