Safe operating practices are established to minimize the known hazards associated with handling hydrogen—fire, explosion, and asphyxiation. Some hazards can be mitigated by hydrogen's unique properties. For example, hydrogen's high dispersion coefficient allows it to dissipate rapidly and makes it virtually impossible for hydrogen to explode in an open area. Other hazards are minimized through operator training and proper system design. Some representative examples include:
- Purging hydrogen systems with an inert gas such as nitrogen is required to avoid the formation of flammable hydrogen/oxygen mixtures.
- Adequate ventilation can minimize or eliminate the potential hazard of asphyxiation and the formation of combustible hydrogen/oxygen mixtures.
- Because hydrogen burns with an almost invisible blue flame, special flame detectors are required.
- Safety systems are integrated into hydrogen vehicle design.
To enable the safety of Hydrogen and Fuel Cell Technologies Office (HFTO)-sponsored projects, a safety plan, which analyzes an entire process, including the personnel, equipment, and environmental components that are directly and indirectly related to a process, is required. A safety plan allows for the quantification of risks, which ultimately promotes the insurability and commercial potential of the project.
Typical Safety Guidelines
Decades of handling hydrogen safely for industrial and aerospace applications provide a wealth of practical experience and established guidelines for safe operating practices. In addition, experience gained through hydrogen and fuel cell vehicle demonstrations has resulted in the development of safe practices for maintaining and operating hydrogen and fuel cell vehicles. These form the basis of safe operating practices for HFTO. Some of the safe hydrogen practices developed through these experiences include the following:
- NASA, with decades of experience using hydrogen as a rocket fuel, has established rigorous safety guidelines for hydrogen system design, materials selection, operations, storage, and transportation.
- The Hydrogen Fuel Cell Engines and Related Technologies Course Manual, produced by the College of the Desert and SunLine Transit Agency with funding from the U.S. Federal Transit Administration, features technical information on the use of hydrogen as a transportation fuel. It covers hydrogen properties, use, and safety as well as fuel cell technologies, systems, engine design, safety, and maintenance.
- As the world's largest supplier of merchant hydrogen and the sole provider of liquid hydrogen for America's Space Shuttle missions, Air Products has summarized the safety precautions for handling materials such as gaseous and liquid hydrogen in its hydrogen safety information Safetygrams. Air Products has also developed hydrogen safety training programs focused on safe handling and properties of hydrogen, and design and operation of hydrogen energy-based systems.