“Interpretation of the New National Standard for High-Purity Hydrogen GB/T 3634.2-2025: Technical Specifications, Testing Methods, and Key Strategies for Enterprises”

  2025 Released in the year GB/T 3634.2-2025 “Hydrogen — Part 2: Pure Hydrogen, High-Purity Hydrogen, and Ultra‑Pure Hydrogen” is an important new national standard for quality control of pure, high-purity, and ultra‑pure hydrogen products in China. Replacing GB/T 3634.2-2011, this standard provides a comprehensive update to the technical requirements, sampling procedures, test methods, inspection rules, labeling, packaging, transportation, storage, and safety information related to high-purity hydrogen.

For hydrogen production companies, gas suppliers, users of electronic-grade specialty gases, enterprises in the hydrogen energy value chain, third-party testing organizations, and laboratories, GB/T 3634.2-2025 is more than just an update to the standard; it also signifies that the evaluation of high-purity hydrogen quality, impurity control, and testing capability development must all be upgraded in tandem.

      Liaoning Kerui Chromatography Technology Co., Ltd. has long been focused on the fields of hydrogen, high-purity gases, and industrial gas detection. This article will center on… New National Standard for High-Purity Hydrogen A systematic interpretation is provided of the basic information, applicable industries, differences between the old and new standards, key indicator requirements, major changes, and the methodological basis corresponding to each test item under GB/T 3634.2-2025.

I. New National Standard Basic Information on GB/T 3634.2-2025

According to the original text of the standard, The basic details of GB/T 3634.2-2025 are as follows:

Project	Content
Standard Number	GB/T 3634.2-2025
Standard Name	Hydrogen gas The Part 2: Pure Hydrogen, High-Purity Hydrogen, and Ultra-Pure Hydrogen
Alternative standard	GB/T 3634.2-2011
Release Date	2025-10-31
Effective Date	2026-05-01
Designated responsible unit	National Technical Committee for Gas Standardization SAC/TC 206
Applicable Subjects	Pure hydrogen, high-purity hydrogen, ultra-pure hydrogen

 

GB/T 3634 “Hydrogen” is divided into two parts:

GB/T 3634.1: Industrial Hydrogen;

GB/T 3634.2: Pure Hydrogen, High-Purity Hydrogen, and Ultra-Pure Hydrogen.

The focus of this interpretation is the second part, namely the purity of Hydrogen products with purities of 99.99%, 99.999%, and 99.9999%.

II. Which industries does GB/T 3634.2-2025 apply to?

GB/T 3634.2-2025 explicitly states that this document applies to pure hydrogen, high-purity hydrogen, and ultrapure hydrogen produced from the following sources:

 

Hydrogen source	Explanation
Hydrogen production via fossil fuel conversion	Such as natural gas reforming and coal-to-hydrogen production, among others.
Hydrogen production via chemical cracking of chemicals	Hydrogen is obtained through the pyrolysis of chemical processes.
Industrial by-product hydrogen	By-product hydrogen from chlor-alkali, coke oven gas, refining, and other processes
Hydrogen-enriched natural gas separation and purification	Separation and purification of hydrogen from hydrogen-enriched natural gas
Hydrogen production via water electrolysis	Alkaline electrolysis, PEM electrolysis, AEM electrolysis, etc.

From the perspective of application industries, high-purity and ultrapure hydrogen are typically used in the following scenarios:

Application Industries	Key Considerations for High-Purity Hydrogen
Electronics and semiconductor industry	Oxygen, nitrogen, moisture, Control of trace impurities such as CO, CO2, and total hydrocarbons
Hydrogen Energy and Fuel Cells	Hydrogen purity, total impurity content, sulfur-containing impurities, CO and other components that affect the stack’s lifespan
Chemical Engineering and Fine Chemicals	Reactor gas purity, catalyst protection, impurity stability
Metal Heat Treatment and Metallurgy	Control of oxygen and moisture in protective and reducing gases
Research Institutes and Testing Organizations	Standard methods, arbitration methods, and consistency of test data
High-purity gas manufacturing enterprise	Factory inspection, batch determination, certificate of quality, filling and traceability

Accordingly, GB/T 3634.2-2025 has a direct impact on high-purity hydrogen producers, gas suppliers, and end‑use gas consumers.

III. New National Standard Differences between GB/T 3634.2-2025 and the previous national standard GB/T 3634.2-2011

and Compared with GB/T 3634.2-2011, GB/T 3634.2-2025, aside from structural adjustments and editorial revisions, incorporates the following major technical changes:

Direction of change	Change Details
Range change	The scope of application of the standard has been revised.
Changes in technical requirements	The technical requirements that pure hydrogen, high-purity hydrogen, and ultrapure hydrogen must meet have been revised.
Sampling Requirements	Sampling requirements have been added; sampling shall comply with GB/T 43306
Purity Calculation	The calculation methods for the purity of pure hydrogen, high-purity hydrogen, and ultrapure hydrogen have been revised.
Impurity Determination	The methods for determining the contents of oxygen, argon, nitrogen, carbon monoxide, and carbon dioxide have been revised.
Total Hydrocarbon Detection	A method for determining total hydrocarbon content has been added.
Moisture Detection	The method for determining moisture content has been revised.
Hydrogen Sulfide Detection	Added a method for determining hydrogen sulfide content.
Exhaust gas treatment	Hydrogen exhaust gas treatment requirements have been added.
Inspection Rules	The rules for batch formation, sampling, judgment, and retesting have been revised.
Logo packaging	The logo, packaging, transportation, and storage requirements have been revised.
Safety Information	Changed the security information requirements.

This indicates that the new version of the standard provides more comprehensive requirements for quality control of high-purity hydrogen, with particular emphasis on sampling, trace impurity analysis, sulfide detection, and safety management throughout the testing process.

IV. Key Indicator Requirements of GB/T 3634.2-2025

GB/T 3634.2-2025 classifies products into three grades: pure hydrogen, high-purity hydrogen, and ultrapure hydrogen. The key specifications are as follows:

Project Name	Indicator
	Pure hydrogen	High-purity hydrogen	Ultra-pure Hydrogen
Hydrogen gas (H ₂ )Purity (mole fraction)	≥99.99×10⁻²	≥99.999×10⁻²	≥99.9999×10⁻²
Oxygen (O ₂ ) Content (mole fraction)	<5×10 ⁻⁶	<1×10 ⁻⁶	<0.1×10- ⁶
Argon (Ar) content (mole fraction)	Supply and demand negotiation	Supply and demand negotiation	<0.2×10- ⁶
Nitrogen (N ₂ ) Content (mole fraction)	<60×10 ⁻⁶	<5×10 ⁻⁶	<0.4×10 ⁻⁶
Carbon monoxide (CO) content (mole fraction)	<5×10- ⁶	<1×10 ⁻⁶	<0.1×10 ⁻⁶
Carbon dioxide (CO ₂ ) Content (mole fraction)	<5×10 ⁻⁶	<1×10- ⁶	<0.1×10 ⁻⁶
Total hydrocarbons Content (mole fraction) (expressed as methane)	<10×10 ⁻⁶	≤1×10 ⁻⁶	<0.3×10- ⁶
Moisture (H ₂ O) Content (mole fraction)	<10×10 ⁻⁶	<3×10 ⁻⁶	<0.4×10 ⁻⁶
Total impurity content (mole fraction)	≤100×10 ⁻⁶	≤10×10 ⁻⁶	≤1.0×10 ⁻⁶
Note  ： The hydrogen sulfide content shall be determined through mutual agreement between the supplier and the purchaser.

As the indicators show, the key challenges in controlling high-purity hydrogen lie in… The focus is primarily on the accurate determination of trace impurities such as oxygen, nitrogen, carbon monoxide, carbon dioxide, total hydrocarbons, and moisture. For ultrapure hydrogen, certain specifications have already entered At the 10⁻⁷ level, higher requirements are imposed on the sensitivity of analytical instruments, system cleanliness, sampling tubing, and method validation capabilities.

V. What is the most significant change in the new national standard?

From the perspective of actual implementation by enterprises, The most significant changes in GB/T 3634.2-2025 can be summarized in three key points:

1. Shifting from “purity outcomes” to “impurity profile control”

The new version of the standard not only specifies hydrogen purity but also explicitly addresses oxygen, nitrogen, and… The total impurity content is calculated for components such as CO, CO₂, total hydrocarbons, and moisture, and the purity is then estimated accordingly.

The standard stipulates that the total impurity content is calculated as the sum of the following components:

Oxygen content; nitrogen content; carbon monoxide content; carbon dioxide content; total hydrocarbon content; moisture content.

This means that companies cannot simply provide a single… A purity result of “99.999%” also requires the capability to perform quantitative analysis of critical impurity species.

2. The testing methodology has become more clearly defined.

GB/T 3634.2-2025 specifies the test method references corresponding to different items, including:

GB/T 6285; GB/T 28726; GB/T 8984; GB/T 5832.2; GB/T 5832.3; GB/T 28727; GB/T 37182; GB/T 43306.

This has a direct impact on laboratory setup, instrument selection, and the issuance of test reports.

3. Add requirements for sampling and exhaust gas treatment.

The new version of the standard has added sampling requirements, stipulating that sampling of pure hydrogen, high-purity hydrogen, and ultrapure hydrogen shall comply with… GB/T 43306 “Gas Analysis — Guidelines for Sampling.”

Meanwhile, the standard includes a warning in the test method: hydrogen exhaust gas must be properly treated during testing to mitigate hydrogen‑related safety risks.

This means that high-purity hydrogen detection is not merely… “Although the instrument can measure,” it is also important to pay attention to:

Sampling representativeness; pipeline cleanliness; system purging; dead volume control; hydrogen venting safety; explosion‑proof measures and exhaust gas treatment.

VI. Methodological Basis for Each Testing Item

GB/T 3634.2-2025 provides clear specifications for the testing methods. The following table shows the correspondence between high-purity hydrogen test items and their respective standard methods.

Test Items	Methodology basis	Explanation
Sampling	GB/T 43306	Sampling of pure hydrogen, high-purity hydrogen, and ultrapure hydrogen shall comply with “Gas Analysis.” Sampling Guidelines
Oxygen O2	GB/T 6285	Determination of trace oxygen in gases by electrochemical methods
Argon Ar	GB/T 28726	Helium Ionization Gas Chromatography
Nitrogen N2	GB/T 28726	Helium Ionization Gas Chromatography
Carbon monoxide CO	GB/T 28726	Helium Ionization Gas Chromatography
Carbon dioxide CO2	GB/T 28726	Helium Ionization Gas Chromatography
Total hydrocarbons, expressed as methane	GB/T 8984	Flame Ionization Gas Chromatography
Water content in pure hydrogen H2O	GB/T 5832.2	Dew Point Method
Water content in high-purity and ultrapure hydrogen H2O	GB/T 5832.3	Cavity Ring-Down Spectroscopy
Hydrogen sulfide H2S	GB/T 28727	Flame Photometric Gas Chromatography
Equivalent methods for O2, Ar, N2, CO, CO2, etc.	GB/T 37182	Plasma Emission Gas Chromatography
Equivalent methods for CO and CO2	GB/T 8984	Flame Ionization Gas Chromatography
Oxygen O2 Equivalent Method	GB/T 28726	Can serve as an equivalent method for determining oxygen content.

It should be noted that, when test results are disputed, the standard also specifies an arbitration method:

1. In case of disagreement regarding the determination of oxygen content, it shall be taken as GB/T 6285 is the arbitration method;

2. When there are discrepancies in the determination of argon, nitrogen, carbon monoxide, and carbon dioxide, the result shall be taken as… GB/T 28726 is the arbitration method;

3. When there is disagreement regarding the determination of hydrogen sulfide, it shall be… GB/T 28727 is the arbitration method;

4. In case of disagreement regarding moisture determination, it shall be considered as The method specified in GB/T 3634.2-2025 is the arbitration method.

VII. How Should Enterprises Respond to the New National Standard for High-Purity Hydrogen?

Facing GB/T 3634.2-2025: High-purity hydrogen producers and testing laboratories are advised to give priority to the following tasks:

1. Verify whether the existing testing capacity is sufficient to cover… O2, N2, Ar, CO, CO2, total hydrocarbons, moisture, H2S, and other parameters;

2. Confirm whether the testing method complies with the national standards cited in the new edition of the standard.

3. Check whether the sampling system meets GB/T 43306 Requirements for Gas Analysis Sampling;

4. The high-purity and ultrapure hydrogen detection pipelines are subjected to purification, inertization, and low‑dead‑volume design.

5. Improve hydrogen tail-gas treatment, explosion-proof venting, and laboratory safety measures;

6. Update the inspection report template, certificate of quality, and product release criteria.

7. For ultrapure hydrogen analysis, assess whether the instrument’s detection limit, repeatability, and calibration system meet the required specifications. Detection requirements at the 10^-7 level.

Liaoning Kerui Chromatography Technology Co., Ltd. can focus on the new national standard for high-purity hydrogen. GB/T 3634.2-2025, in conjunction with gas chromatography, helium ionization detection, flame ionization detection, sulfide detection, moisture analysis, and sampling systems, provides consulting on high-purity hydrogen testing solutions and instrument configuration recommendations for gas producers, testing laboratories, and gas‑using entities.

VIII. GB/T 3634.2-2025 Frequently Asked Questions

1. What is the GB/T 3634.2-2025 standard?

GB/T 3634.2-2025 is the national standard titled “Hydrogen — Part 2: Pure Hydrogen, High-Purity Hydrogen, and Ultra‑Pure Hydrogen,” which specifies the technical requirements, sampling procedures, inspection rules, test methods, labeling, packaging, transportation, storage, and safety information for pure hydrogen, high-purity hydrogen, and ultra‑pure hydrogen.

2. When will GB/T 3634.2-2025 come into effect?

GB/T 3634.2-2025 was published on October 31, 2025, and will come into effect on May 1, 2026.

3. Which standard does GB/T 3634.2-2025 replace?

GB/T 3634.2-2025 supersedes GB/T 3634.2-2011.

4. What is the required purity level for high-purity hydrogen?

According to GB/T 3634.2-2025 specifies that the purity of high-purity hydrogen (H₂) shall be ≥99.999×10⁻², which corresponds to the commonly referred to grade of 99.999% high-purity hydrogen.

5. What is the required purity level of ultrapure hydrogen?

Ultra-pure hydrogen The H2 purity requirement is ≥99.9999×10⁻², which corresponds to the commonly referred to as 99.9999%–grade ultrapure hydrogen.

6. What impurities need to be detected in high-purity hydrogen?

High-purity hydrogen is primarily analyzed for oxygen, nitrogen, carbon monoxide, carbon dioxide, total hydrocarbons, and moisture. The argon content is determined through mutual agreement between the supplier and the purchaser, and the hydrogen sulfide content is likewise agreed upon by both parties.

7. What methods are commonly used for detecting high-purity hydrogen?

GB/T 3634.2-2025 covers the following principal methods: GB/T 6285, GB/T 28726, GB/T 8984, GB/T 5832.2, GB/T 5832.3, GB/T 28727, GB/T 37182, and GB/T 43306.

Conclusion

The publication and implementation of GB/T 3634.2-2025 mark the entry of China’s quality control for pure hydrogen, high-purity hydrogen, and ultrapure hydrogen into a new phase characterized by greater systematization, standardization, and refinement. The revised standard not only focuses on hydrogen purity but also places particular emphasis on trace impurity detection, sampling protocols, methodological foundations, and safety management.

For high-purity hydrogen producers, hydrogen energy companies, users of electronic-grade gases, and testing organizations, it is essential to gain an early understanding. GB/T 3634.2-2025: Establishing a testing system that complies with the new national standard is a crucial foundation for ensuring product quality, enhancing customer trust, and meeting market access requirements.

Liaoning Kairui Chromatography Technology Co., Ltd. will continue to focus on high-purity hydrogen detection, high-purity gas analysis, and… With the implementation of GB/T 3634.2-2025, we provide industry clients with professional chromatographic analysis technical support, testing solutions, and instrument configuration recommendations.