GB/T 3634.1-2025Hydrogen - Part 1: Industrial hydrogen (English PDF)

6.2.1 Thermal conductivity gas chromatography

6.2.1.1 Overview of method A gas chromatograph equipped with a thermal conductivity detector (TCD) was used, with high-purity hydrogen as the carrier gas. The TCD operates based on the thermal conductivity effect, i.e., different substances have different thermal conductivities. Industrial hydrogen was 7 - Sample gas inlet; 8 - Tail gas outlet; 9 - Thermal conductivity detector; 10 - Chromatographic column; 11 - Balance gas flow controller. Figure 1 -- Schematic diagram of thermal conductivity gas chromatography flow chart

6.2.1.3 Reagents and materials 6.2.1.3.1 Carrier gas High-purity hydrogen shall meet the requirements of GB/T 3634.2. 6.2.1.3.2 Chromatographic column A stainless-steel tube approximately 6000 mm long and 2 mm in inner diameter, packed with modified calcium molecular sieve (referred to as "5A molecular sieve") with a particle size of

0.25 mm to

0.40 mm; or other equivalent chromatographic columns. 6.2.1.3.3 Gas standard sample The content of the component shall be as close as possible to that of the content of the tested component. Hydrogen shall be used as the equilibrium gas.

6.2.1.4 Measurement conditions 6.2.1.4.1 Carrier gas flow rate It is recommended to be 40 mL/min, or refer to the instrument manual. 6.2.1.4.2 Bridge current It is recommended to be 150 mA, or refer to the corresponding instrument manual. 6.2.1.4.3 Other conditions Refer to the instrument manual.

6.2.1.5 Measurement procedure After the instrument has stabilized, perform the measurement according to the instrument manual. Measure the gas standard sample and sample gas in parallel for at least three times, until the difference between two consecutive measurements is no greater than 5% of the arithmetic mean of these three measurements. Take the arithmetic mean of these three measurements as the final measured value. A typical chromatogram is shown in Appendix A.

6.2.1.6 Processing of the results The nitrogen and (oxygen + argon) content (xs,i) in the sample gas is calculated according to Formula (2). Where. xs,i - the content (mole fraction) of target component i in the sample gas; s,i - the arithmetic mean of the response values of target component i in the sample gas; r,i - the arithmetic mean of the response values of target component i in the gas standard sample/standard substance; xr,i - the content (mole fraction) of target component i in the gas standard sample/standard substance.

6.2.2 Equivalent methods Other equivalent methods may be used to determine the nitrogen and oxygen + argon content in industrial hydrogen. In case of disagreement over the determination results, the method specified in

6.2.1 shall be used as the arbitration method.

6.3 Determination of moisture content The determination of moisture content in industrial hydrogen with a purity of 99.95% shall be performed in accordance with the provisions of GB/T 5832.2.Other equivalent methods may also be used to determine the moisture content in industrial hydrogen. In case of disagreement over the determination results, the method specified in GB/T5832.2 shall be used as the arbitration method.