CGA’s H-5 Publication Guides Safe Design, Installation, and Use of Bulk Hydrogen Supply Systems

October 22, 2020

As demand for hydrogen grows, it is vital that systems for supplying hydrogen to end users be robust and safe. In September 2020, the Compressed Gas Association (CGA) issued the 3rd edition of CGA H-5, Standard for Bulk Hydrogen Supply Systems (an American National Standard).

This recently revised safety standard provides minimum requirements for locating/siting, selecting equipment, installing, starting up, maintaining, and removing bulk hydrogen supply systems.

CGA H-5 is referenced in the National Fire Protection Association’s NFPA 55 Compressed Gases and Cryogenic Fluids Code.

Bulk Hydrogen Supply Systems

Bulk hydrogen supply systems covered by this standard are either liquid or gaseous and operate at pressures up to 15 000 psi (103.4 MPa).

Bulk hydrogen supply systems often include the following, although not all hydrogen supply systems include all the equipment shown:

  • cryogenic hydrogen storage tanks, either aboveground or belowground
  • gas storage vessels (receivers), either aboveground or belowground
  • vaporizers
  • valves including manual and automatic shutoff valves and check valves
  • pressure control equipment including regulators and control valves
  • piping (pipe and tubing)
  • cryogenic pumps
  • cryogenic and warm gas compressors
  • snubbers and pulsation dampeners
  • monitoring and control systems, including electrical and instrumentation

The bulk hydrogen supply system terminates at the source valve where the gaseous or liquid hydrogen supply first enters the supply line to the customer.

Liquid vs. Gaseous Supply Systems

The CGA H-5 safety standard covers two types of bulk hydrogen supply systems: liquid and gaseous. A bulk liquid supply system is one that contains more than 39.7 gallons (150 L) of hydrogen. A bulk gas hydrogen supply system is one that contains more than 5000 scf (141.6 m3) of hydrogen.

A liquid system is one in which hydrogen is delivered to the supply system and stored on-site in liquid form. Hydrogen is then supplied to the customer in either liquid or gaseous form, depending on the customer’s requirement.

When required, pumps and/or compressors are used to increase the hydrogen pressure before it is supplied to the customer. When required, coded vessels are used to store gaseous hydrogen before it is supplied to the end user. The system is considered to be a bulk liquid system instead of a bulk gaseous system because the hydrogen is delivered from the hydrogen supplier to the storage system in liquid form.

In contrast, a gaseous system is one in which hydrogen is delivered to the supply system, stored, and supplied to the customer’s requirement, all in gaseous form.

What’s Covered in CGA H-5

This safety standard includes:

  • Work process (from start to finish) for a hydrogen supply system;
  • Review of applicable codes and standards that hydrogen supply systems must meet;
  • Guidance for meeting OSHA Process Safety Management and EPA Risk Management Program requirements for large (over 10,000 pounds) hydrogen supply systems;
  • Details for selecting equipment suitable for hydrogen service;
  • Procedures for testing a new system before putting it in service;
  • Flow diagrams covering a range of typical hydrogen supply systems to aid in hydrogen system design

The full Table of Contents may be downloaded for free from the CGA H-5 publication details page on the CGA portal.

Learn More About CGA’s Expanding Role in the Hydrogen Energy Revolution

Members of the Compressed Gas Association have long been global leaders in the production, storage, distribution, and application of hydrogen and other industrial gases.

In addition to our existing library of hydrogen standards, we are bringing our unique expertise in hydrogen to the development of new standards for emerging applications in the hydrogen-powered transportation space.

A complete list of CGA’s hydrogen-related safety standards, as well as details about our recently-announced Hydrogen Initiative, may be viewed here.