ISO 22734-1-2025 PDF

Full title and description

Hydrogen generators using water electrolysis — Part 1: Safety. This International Standard specifies safety requirements for appliances or systems that produce hydrogen by electrolysis of water (hereafter "hydrogen generators"), addressing hazards associated with hydrogen production, storage interfaces, electrical systems and ancillary equipment.

Abstract

This document sets out mandatory safety requirements and related guidance for design, construction, installation and operation of hydrogen generators that use electrochemical water electrolysis. It covers risk assessment, protective measures (ventilation, detection, electrical protection), pressure and fluid handling, marking and instructions, and tests to verify safe operation for intended applications.

General information

• Status: Published
• Publication date: 3 July 2025
• Publisher: International Organization for Standardization (ISO)
• ICS / categories: 71.100.20, 71.120.99
• Edition / version: Edition 1 (2025)
• Number of pages: 63

Scope

The standard applies to hydrogen gas generation appliances or systems that use electrochemical reactions to electrolyse water to produce hydrogen. It is intended to define safety requirements for such generators across industrial, commercial and residential contexts where appropriate, excluding systems that fall outside the defined product/appliance scope (see full text for detailed exclusions and applicability criteria).

Key topics and requirements

• Risk assessment and identification of hydrogen‑related hazards (flammability, overpressure, electrical, corrosive products).
• Design and construction requirements for cells, stacks, balance‑of‑plant and enclosures to minimise leak, ignition and overpressure risks.
• Electrical safety (protection, isolation, earthing) for electrolyser systems and associated power electronics.
• Ventilation, purging and hydrogen detection requirements for indoor and sheltered installations.
• Requirements for pressure-containing parts, piping, valves and interfaces with gas distribution or storage systems.
• Testing, verification and inspection procedures to confirm compliance with safety requirements.
• Marking, documentation, operator instructions and maintenance requirements.
• Requirements for installation, commissioning and safe decommissioning procedures.

Typical use and users

Used by electrolyser and hydrogen‑generator manufacturers, system integrators, safety and design engineers, test laboratories, certifying bodies, installation contractors, plant operators and regulators to specify, assess and demonstrate safe design and operation of water‑electrolysis hydrogen generators in industrial, commercial and covered residential settings.

Related standards

ISO 22734-1:2025 supersedes ISO 22734:2019 (withdrawn) and is published as the first part of a revised series. Related documents and standards include the developing ISO/WD TS 22734-2 (testing guidance for grid‑service capabilities), other ISO/TC 197 outputs, and complementary standards such as ISO 19880‑1 (gaseous hydrogen — fuelling stations), ISO 26142 (hydrogen detectors), and relevant IEC standards for electrical and explosive‑atmosphere protection referenced in the normative clauses.

Keywords

hydrogen generator, water electrolysis, electrolyser safety, PEM, alkaline electrolyser, risk assessment, hydrogen detection, ventilation, pressure equipment, marking, commissioning, test procedures.

FAQ

Q: What is this standard?

A: ISO 22734-1:2025 is an International Standard that specifies safety requirements for hydrogen generators that produce hydrogen by electrolysing water (electrolysers).

Q: What does it cover?

A: It covers design, construction, installation, testing, marking and documentation requirements aimed at preventing and managing hazards associated with hydrogen production by electrolysis, including electrical, flammability and pressure risks. For full clause‑level detail consult the published text.

Q: Who typically uses it?

A: Manufacturers, integrators, test labs, certifiers, installers, operators and regulators involved with electrolyser systems and hydrogen generation equipment.

Q: Is it current or superseded?

A: ISO 22734-1:2025 is the current published standard (issued 3 July 2025) and replaces the earlier consolidated ISO 22734:2019, which has been withdrawn.

Q: Is it part of a series?

A: Yes — the 2025 publication is published as Part 1 (safety) of a revised series for hydrogen generators. Additional parts and technical specifications (for example, testing guidance / grid‑service testing) are in development (ISO/WD TS 22734‑2 and other ISO/TC 197 work items).

Q: What are the key keywords?

A: hydrogen generator; water electrolysis; electrolyser; safety; PEM; alkaline; risk assessment; hydrogen detection; pressure equipment; ventilation; test procedures.