This guide is intended to promote safe designs, operations and maintenance on aircraft and ground support oxygen systems. This is also a summary of some work by the ASTM G 4 Committee related to oxygen fire investigations and design concerns to reduce the risk of an oxygen fire. There have been many recent technological advances and additional test data is available for evaluating and controlling combustion hazards in oxygen equipment. Standards that use this new information are rapidly evolving. A guide is needed to assist organizations and persons not completely familiar with this process to provide oxygen systems with minimum risks of combustion. This guide does not necessarily address all the detailed issues and provide all data that will be needed. For a complete analysis, supplemental publications need to be consulted. This guide does discuss the basics of oxygen systems fire hazards. The hazard analysis process is discussed and a simple example to explain this process. Also, this guide does not address the overall system safety issues normally evaluated in aircraft programs. This guide does provide some important background and observations about combustion in oxygen systems. Information is given describing how to accomplish a hazard analysis. Furthermore, background is provided to explain critical locations in oxygen systems that need to be evaluated and other locations that do not require hazard analysis.