GB 5274-1985 Gas analysis - Preparation of mixed gases for calibration - Weighing method

The weighing method is only applicable to gases that do not react with each other or with the inner wall of the gas cylinder, as well as condensable components that are completely in the gaseous state under experimental conditions. GB 5274-1985 Gas analysis - Preparation of mixed gases for calibration - Weighing method GB5274-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Gas analysis-Preparation of calibration gas mixtures-Weighing methods UDC543.27
:53.089.68
GB 5274.85
This standard describes the weighing method used to prepare calibration gas mixtures. The mixed gas prepared by this method. Within the concentration range specified in this standard, regardless of the selected concentration value, the uncertainty of the concentration of each component is less than 1%. This standard is equivalent to the international standard IS06142--1981 "Gas analysis-Preparation of calibration gas mixtures: Weighing method". 1 Scope of application www.bzxz.net
The weighing method is only applicable to gases that do not react with each other or with the inner wall of the gas cylinder, as well as condensable components that are completely in the gaseous state under experimental conditions.
2 Principle of the method
2.1 General principle
Weigh the gas cylinder before and after filling it with a certain amount of a gas component of known purity, and determine the mass of the gas component filled in the gas cylinder by the difference in the code readings of the two weighings. Filling the gas with various components will produce a mixed gas. The mass concentration of each component in the mixed gas is the ratio of the mass of the component to the total mass of all components. The molar concentration of each component in the mixed gas is the ratio of the molar number of the component to the total molar number of all components. In order to avoid weighing too small an amount of gas, a lower concentration limit should be set for the concentration of each component in the prepared mixed gas, or the small amount of the component should be filled into a smaller gas cylinder separately, weighed on a balance with a small maximum weighing capacity, and then the component is transferred to another gas cylinder without loss, and the gas with a large component is weighed on a balance with a large maximum weighing capacity. If the concentration to be prepared is lower than the specified lower limit, a certain amount of the previously prepared mixed gas should be diluted with a known amount of gas. In order to obtain a gas mixture with a molar concentration of 10-6, within the permissible error, the dilution operation must be repeated twice. This error depends on the performance of the balance and the operating procedure used. Under these conditions, the concentration is calculated as follows. Note: The basic unit of "mole" mentioned in this standard is molecule. 2.1.1 Single dilution method
This method is applicable to the preparation of mixed gas with a concentration range of 10≤X≤1 (mol). The concentration of component i in the mixed gas (mixed gas a) is calculated by the following formula:
Where: ije(lP,ji
The symbol of the component in the mixed gas. The molar concentration is the total number of components in the mixed gas of X, X;
The mass is m; The molar number of component i with a molar mass of M., that is: n=articles; n
-The molar number of component i with a mass of mi and a molar mass of M;, that is, njNational Bureau of Standards 1985-08-01 Issued
Free Customs
1986-06-01 Implementation
GB 5274-85
In the following text and in the error calculation, the following quantitative relationship is also used: m =mi+2mj
n =ni+Enj
2.1.2 Secondary dilution method
This method is suitable for preparing the concentration range of 10*4
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