Submarines operate in one of the most hostile environments on Earth, completely isolated from the surface world for weeks or even months. The fundamental question of how do submarines make oxygen is critical for survival, as the crew must breathe in a sealed, pressurized vessel. Unlike a surface ship that constantly draws fresh air from the atmosphere, a submarine must carry its own breathable air and manage the complex science of gas exchange internally.
Chemical Oxygen Generation: The Primary Lifeline
The most reliable and immediate method submarines use to sustain breathable air is through chemical oxygen generation. This process relies on specialized compounds, most commonly chlorate candles, which are ignited to produce oxygen gas through a controlled exothermic reaction. These candles are a cornerstone of the submarine's life support system, providing a high-output source of oxygen that does not rely on external inputs once activated.
Mechanics of Chlorate Candles
Chlorate candles contain a compound such as sodium chlorate mixed with iron powder and other catalysts. When ignited, the heat triggers a decomposition reaction where the chlorate releases oxygen molecules. The iron powder serves as a fuel, helping to sustain the reaction and generate heat, which in turn ensures a consistent and robust flow of oxygen gas into the ship's atmosphere.
Onboard Oxygen Storage and Distribution
While chemical generators are vital for emergencies and high-consumption periods, submarines also rely on sophisticated storage systems for routine operations. Large, high-pressure tanks store oxygen gas that is produced during maintenance cycles or by other means. This stored oxygen is then carefully regulated and distributed throughout the vessel via a network of valves and pipelines to ensure every compartment maintains the correct atmospheric balance.
Atmosphere Control: Balancing Gases for Survival
Oxygen generation is only one part of the equation; managing the entire atmosphere is equally crucial. Submarines must not only add oxygen but also remove the carbon dioxide exhaled by the crew. If CO2 levels rise unchecked, they can cause headaches, lethargy, and ultimately suffocation, making air revitalization a constant priority.
The Role of Carbon Dioxide Scrubbers
To maintain air quality, submarines utilize carbon dioxide scrubbers, which typically contain a chemical called soda lime. As air passes through these scrubbers, the soda lime chemically binds to the carbon dioxide, effectively removing it from the breathable mixture. This process is continuous and allows the submarine to recirculate the majority of the air, conserving the precious oxygen supply while keeping the environment safe.
Emergency Systems and Redundancy
Safety is paramount in the confined space of a submarine, and oxygen management is no exception. Vessels are equipped with multiple redundant systems to ensure the crew can survive any scenario. Emergency oxygen is stored in dedicated escape breathing apparatus and can be deployed instantly if the main atmosphere control systems fail or if the submarine needs to surface rapidly.
Escape Immersion Equipment
For extreme emergencies, such as a need to abandon ship, submarines provide individual breathing apparatus. These devices, often referred to as escape sets, contain a small, self-contained oxygen or chemical CO2 scrubber system. They are designed to sustain a single sailor for the duration of an escape through the water, providing a critical last line of defense when surfaced air is inaccessible.
Surface Support and Routine Maintenance
Even the most advanced submarine must eventually return to port for deep maintenance. During extended deployments, the vessel relies on its stored oxygen and generated oxygen, but a significant portion of the breathable atmosphere is refreshed when docked. At the pier, submarines connect to shore-based air systems that pump in freshly treated oxygen and remove stale air, resetting the life support systems for the next mission.
