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Welcome to Smarter Every Day, where we delve into the fascinating world of science and technology. Today, we're taking a deep dive into a question that has always intrigued me: How do submarines generate oxygen while submerged?
Submarines are designed to remain submerged for extended periods, sometimes unable to surface for fresh air. So, how do they maintain a breathable atmosphere for their crew? In this article, we'll explore the innovative methods used to create oxygen and remove carbon dioxide from the air within a submarine.
To ensure the air quality within a submarine is safe for its crew, a sophisticated system called the Central Atmospheric Monitoring System (CAMS) is employed. CAMS constantly monitors the atmosphere in various compartments, measuring the levels of oxygen, carbon dioxide, and other gases. If any of these levels become unsafe, an alarm is triggered, alerting the crew to take appropriate action.
There are two primary methods for generating oxygen on a submarine:
The first method involves using electrolysis to split water molecules into hydrogen and oxygen. However, using seawater directly for this process would be dangerous, as it would produce chlorine gas, which is harmful to humans. Instead, seawater is first purified through a filtration system and reverse osmosis to remove salts and impurities. This purified water is then electrolyzed using potassium hydroxide (KOH) as a catalyst, producing oxygen and hydrogen gas. The oxygen is released into the submarine's atmosphere, while the hydrogen is safely vented overboard.
The second method for generating oxygen is through the use of oxygen candles. These candles contain a mixture of iron and sodium chlorate. When ignited, the iron burns, creating heat and iron oxide. This heat causes the sodium chlorate to release oxygen, providing a reliable source of oxygen even in the event of a power outage. Oxygen candles are compact and efficient, making them an essential backup method for oxygen generation.
As the crew breathes, carbon dioxide is released into the atmosphere. To maintain a safe level of CO2, submarines employ two primary methods for removing it:
The MEA system is a chemical scrubber that removes CO2 from the air by absorbing it into a liquid solution of monoethanolamine. This solution is then heated, causing the CO2 to be released and compressed. The compressed CO2 is then vented overboard, while the now "lean" MEA solution is reused to absorb more CO2.
Lithium hydroxide canisters are a passive method for removing CO2 from the atmosphere. When exposed to air, lithium hydroxide absorbs CO2, converting it into lithium carbonate. This process is used in various applications, including rebreathers for Navy SEALs and space suits for astronauts. Lithium hydroxide canisters are an essential backup for removing CO2 in the event of a power outage or failure of the MEA system.
The ability to generate oxygen and remove carbon dioxide is crucial for the survival of submariners during extended periods at sea. Through innovative methods such as electrolysis, oxygen candles, the MEA system, and lithium hydroxide canisters, submarines can maintain a safe and breathable atmosphere for their crew, allowing them to remain submerged for weeks or even months at a time.
I hope this article has provided you with a deeper understanding of the fascinating science behind submarine oxygen generation. Stay tuned for more episodes of Smarter Every Day, where we continue to explore the wonders of science and technology.
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