Emergency Atmosphere Control; Design and Operational Experience

This paper will report US Navy submarine philosophy and test experience with the emergency atmosphere control system. A vital aspect of emergency recovery within contained environments is the ability to maintain life while directing escape or awaiting rescue. Emergency atmosphere control differs from primary life support in several key areas. The primary atmosphere control system provides a habitable atmosphere so that the crew can live comfortably and work efficiently in an enclosed environment. Additionally the primary atmosphere control system controls chronic and acute toxicants to minimize both short and long term health consequences. For long duration missions, primary atmosphere control is generally regenerative and may include redundant components for reliability. The emergency life support system replaces the primary system in the event of a catastrophic failure. In emergency situations, the crew's comfort and their exposure to trace levels of toxic species are no longer design drivers. As the emergency atmosphere control system is already redundant to the primary system, further back-ups are not typically employed. The US submarine Navy employs emergency oxygen supply, carbon dioxide removal and atmosphere analysis on all nuclear powered submarines. As emergency life support is intended to back-stop the main system, it must operate completely independently of the main (regenerative) system. Operating without the normal submarine interfaces (power, cooling, ventilation) places large restrictions on the design of emergency life support. This paper will report on the evolution of those requirements. Design and operation of the components will be discussed. Concepts to recover from certain casualties will also be provided.