Analysis accuracy of standard gas

1. General rules for standard gas preparation

The development process of standard gas can be divided into four steps: purity analysis of raw material gas; composition pressure preparation by weighing method: calibration by high-precision analysis methods such as gas chromatography and chemiluminescence; performance inspection and packaging conditions. The development and producer of the standard gas shall ensure that there are detailed technical information and reproducible descriptive documents for the standard gas to guide the preparation process, and ensure the normal use of the equipment required for preparation. All preparation processes should be carried out and controlled in accordance with predetermined preparation procedures to avoid being affected by outsiders or the environment.

2. Purity analysis of raw gas prepared by standard gas

The standard gas has very high requirements for the accuracy of the provided characteristic values. The quality of the raw gas should be controlled before preparation. If you want to prepare the CO, CH4, CO2/N2 quaternary standard gas with a content of less than 100*10-6, The dilution gas is high-purity nitrogen, and the content of related impurities CO, CH4, and CO2 must be accurately analyzed and determined. Obviously, the contents of CO, CH4, and CO2 in nitrogen will all be introduced into the standard gas during the preparation of the standard gas and directly affect the result of the setting, especially when the standard gas with a lower content is prepared, the influence is more prominent. . The purity analysis of raw gas is a basic research work, which directly affects the determination result of the weighing method. There are three problems to be solved in the analysis of raw gas, namely, the content of the main body, the content of the components to be formulated in the dilution gas, and the content of the components that interfere with the components to be formulated. This requirement is quite harsh, which will inevitably lead to research on gas analysis technology and purification technology. From this point of view, in the standard gas preparation process, the requirements for analysis technology and purification technology are quite high.

When the raw material gas required for preparation cannot meet the production requirements of the standard gas, it should be repurified to ensure the effectiveness of the above preparation process and operation process.