Preparation of standard gases with special properties

1. Preparation of standard gas with lively properties

Some gases are very active and easily react with oxygen and water packaging container materials to change the concentration. These gases were previously prepared in small quantities by methods such as ampoules and saturated vapor pressure, and are not suitable for long-distance transportation and long-term storage. In the 1980s, NIST and some special gas companies such as SCOTT developed the inner coating technology of steel cylinders through experiments. This technology effectively prevents the reactive gas from reacting with the inner wall of the steel cylinder, which increases the stability of the gas, but the stability of the gas is limited to half a year, and the longest is not more than one year. The prepared standard gas does not form the value transfer and traceability.

2. Preparation of volatile organic compound standard gas

Volatile organic compounds are an important indicator of indoor air pollution. In the past, such standard gases were prepared by infiltration or diffusion methods. Different concentrations of standard gases were obtained by changing the temperature and the geometry of the diffusion tube. As early as the early 1980s, the United States developed a method for accurately weighing trace liquids with capillary tubes. At present, there are as many as 39 VOCs standard gases with traceable NIST values.

In recent years, with the introduction and digestion of the world's advanced gas distribution technology and the efforts of several generations of scientific researchers in my country, my country has achieved rapid development in the preparation of standard gases, and the preparation of gases in the range of constant and semi-trace concentrations has formed metering Traceability system and can be compared with international reference materials.