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

6.1 Calculation of industrial hydrogen purity

The chlorine, alkali, and moisture content in industrial hydrogen is not included in the purity calculation. The purity of industrial hydrogen is calculated according to Formula (1).

Where: x - purity of industrial hydrogen (mole fraction); x1 - nitrogen content (mole fraction); x2 - (oxygen + argon) content (mole fraction).

6.2 Determination of nitrogen, oxygen + argon content

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 […]

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.

7.1 Batching

A batch consists of industrial hydrogen products packaged in cylinders produced continuously and stably from the same production line. For industrial hydrogen packaged in cylinder bundles, long-tube trailers, or large-capacity seamless steel cylinders, each package of industrial hydrogen constitutes a batch. […]