This Technical Memorandum was originally prepared as an Annex on the topic of Hydrogen Embrittlement for the AIAA Guide to Safety of Hydrogen and Hydrogen Systems (G-095-2004), then in revision [1]. The Guide establishes a uniform NASA process for hydrogen system design, materials selection operation, storage and transportation, and represents a broad collection of aerospace acumen.

In collaboration with Parker Hannifin Corporation, the Fire Safety Branch of the FAA conducted testing to evaluate the effects of three potential failure conditions of hydrogen proton exchange (or polymer electrolyte) membrane fuel cell stacks supplied by Nuvera Fuel Cells. The three conditions examined were a loss of coolant to the stack, short circuit, and a crossflow condition.

This document and its companion document, Safety Standard for Oxygen and Oxygen Systems (NSS1740.151996),are identified as Tier 2 Standards and Technical Requirements in the NASA Safety and Documentation Tree (NHB 1700.1 1993). The information presented is intended as a reference to hydrogen design and practice and not as an authorizing document. The words "shall" and "must" are used in this document to indicate a mandatory requirement, and the authority for the requirement is given.