1. Calibration gas include: gas alarm standard gases, electric energy standard gases, petrochemical standard gases, environmental monitoring standard gases, medical and health standard gases, instrument and meter standard gases, etc.

     2. Standard gas can also be used for environmental monitoring, toxic organic matter measurement, vehicle emission gas test, natural gas BTU measurement, LPG calibration standard, supercritical fluid process, etc. Standard gas group fraction is divided into binary, ternary and multivariate standard gases. The accuracy of distribution is characterized by distribution tolerance and analysis tolerance. SE2MI gas distribution tolerance standard is more general, but each company has enterprise standard. The lowest concentration of the component is grade 10, and the group fraction can be as many as 20 kinds. The preparation method may be gravimetric and then checked by chromatographic analysis, or transmitted according to the standard transfer procedure.

     3. In large vinyl factories, synthetic ammonia plants and other petrochemical enterprises, dozens of pure gases and hundreds of standard multi-component mixed gases are needed for calibration and calibration of on-line analytical instruments used in the production process and for analysis of raw materials and product quality during start-up, shutdown and normal production.