NFPA 55, Compressed Gases and Cryogenic Fluids Code has requirements for separation distances between gas hydrogen systems and outside exposures in Chapter 10[1]. It also has requirements for separation distances between liquid hydrogen systems and outside exposures in Chapter 11. However, installers of hydrogen systems sometimes encounter exposures that are not defined in the separation distance tables. Installers also find that the wording about some exposures is not clear and needs better definition.