## What is a Rebreather in Scuba Diving?
A rebreather is a scuba diving apparatus that recycles the diver’s exhaled breath, removing carbon dioxide and replenishing oxygen. This allows the diver to stay underwater for longer periods of time than with traditional open-circuit scuba gear, which vents exhaled breath into the surrounding water.
There are two main types of rebreathers:
Closed-circuit rebreathers (CCR) recycle all of the diver’s exhaled breath, with no gas being released into the water. This makes CCRs very efficient, but also more complex and expensive to operate than open-circuit gear.
Semi-closed-circuit rebreathers (SCR) recycle most of the diver’s exhaled breath, but a small amount of gas is released into the water to prevent the diver from rebreathing their own carbon dioxide. SCRs are less efficient than CCRs, but they are also simpler and less expensive to operate.
Rebreathers offer several advantages over traditional open-circuit scuba gear, including:
Longer dive times: Rebreathers allow divers to stay underwater for hours or even days at a time, depending on the size of the rebreather and the diver’s breathing rate.
Reduced gas consumption: Rebreathers recycle the diver’s exhaled breath, which reduces the amount of gas that is needed to be carried. This can be a significant advantage for divers who are diving in remote areas or who need to travel long distances underwater.
Increased stealth: Rebreathers do not release bubbles into the water, which makes them ideal for diving in areas where stealth is important, such as military operations or underwater photography.
Reduced environmental impact: Rebreathers do not release any gas into the water, which helps to protect the environment.
Rebreathers also have some disadvantages, including:
Complexity: Rebreathers are more complex to operate than open-circuit scuba gear, and they require specialized training to use safely.
Cost: Rebreathers are more expensive to purchase and maintain than open-circuit scuba gear.
Risk of oxygen toxicity: Rebreathers can expose divers to high levels of oxygen, which can lead to oxygen toxicity if not properly managed.
Overall, rebreathers are a specialized piece of scuba diving equipment that can offer significant advantages over traditional open-circuit gear. However, they are also more complex and expensive to operate, and they require specialized training to use safely.
## How Does a Rebreather Work?
A rebreather works by recycling the diver’s exhaled breath, removing carbon dioxide and replenishing oxygen. The process of recycling breath is called a “closed circuit.”
The diver’s exhaled breath is first passed through a scrubber, which removes carbon dioxide. The carbon dioxide is absorbed by a chemical compound, such as soda lime or potassium hydroxide.
The scrubbed breath is then passed through an oxygen sensor, which measures the partial pressure of oxygen in the gas. If the oxygen level is too low, the rebreather will automatically add oxygen to the gas mixture.
The oxygenated gas is then passed through the diver’s breathing loop, which is a closed circuit that includes the diver’s mouthpiece, breathing hose, and rebreather canister. The diver inhales the oxygenated gas from the breathing loop, and the cycle repeats.
## Types of Rebreathers
There are two main types of rebreathers: closed-circuit rebreathers (CCR) and semi-closed-circuit rebreathers (SCR).
### Closed-Circuit Rebreathers (CCR)
CCR recycle all of the diver’s exhaled breath, with no gas being released into the water. This makes CCRs very efficient, but also more complex and expensive to operate than open-circuit gear.
CCR use a counter-lung system to store the diver’s exhaled breath. The counter-lung is a collapsible bag that is located inside the rebreather canister. When the diver exhales, the exhaled breath is stored in the counter-lung. When the diver inhales, the exhaled breath is drawn from the counter-lung and passed through the scrubber and oxygen sensor.
CCR have a number of advantages over SCR, including:
Longer dive times: CCRs can allow divers to stay underwater for hours or even days at a time, depending on the size of the rebreather and the diver’s breathing rate.
Reduced gas consumption: CCRs recycle all of the diver’s exhaled breath, which reduces the amount of gas that is needed to be carried. This can be a significant advantage for divers who are diving in remote areas or who need to travel long distances underwater.
### Semi-Closed-Circuit Rebreathers (SCR)
SCR recycle most of the diver’s exhaled breath, but a small amount of gas is released into the water to prevent the diver from rebreathing their own carbon dioxide. SCR are less efficient than CCR, but they are also simpler and less expensive to operate.
SCR use a venturi system to add oxygen to the diver’s exhaled breath. The venturi system is a small tube that is located in the rebreather canister. When the diver inhales, the venturi system creates a vacuum that draws oxygen from the rebreather’s oxygen supply. The oxygen-enriched gas is then mixed with the diver’s exhaled breath and passed through the scrubber.
SCR have a number of advantages over CCR, including:
Simplicity: SCR are simpler to operate than CCR, and they require less training to use safely.
Cost: SCR are less expensive to purchase and maintain than CCR.
## Advantages of Rebreathers
Rebreathers offer several advantages over traditional open-circuit scuba gear, including:
Longer dive times: Rebreathers allow divers to stay underwater for longer periods of time than with open-circuit gear. This is because rebreathers recycle the diver’s exhaled breath, which reduces the amount of gas that is needed to be carried.
Reduced gas consumption: Rebreathers recycle the diver’s exhaled breath, which reduces the amount of gas that is needed to be carried. This can be a significant advantage for divers who are diving in remote areas or who need to travel long distances underwater.
Increased stealth: Rebreathers do not release bubbles into the water, which makes them ideal for diving in areas where stealth is important, such as military operations or underwater photography.
Reduced environmental impact: Rebreathers do not release any gas into the water, which helps to protect the environment.
## Disadvantages of Rebreathers
Rebreathers also have some disadvantages, including:
Complexity: Rebreathers are more complex to operate than open-circuit scuba gear, and they require specialized training to use safely.
Cost: Rebreathers are more expensive to purchase and maintain than open-circuit scuba gear.
Risk of oxygen toxicity: Rebreathers can expose divers to high levels of oxygen, which can lead to oxygen toxicity if not properly managed.
## Who Should Use a Rebreather?
Rebreathers are not for everyone. They are best suited for experienced divers who are willing to invest the time and money to learn how to use them safely and effectively.
Divers who may benefit from using a rebreather include:
Technical divers: Technical divers often need to stay underwater for longer periods of time than recreational divers. Rebreathers can allow technical divers to extend their dive times significantly.
Cave divers: Cave divers often need to be able to travel long distances underwater, and they need to be able to do so without disturbing the environment. Rebreathers can allow cave divers to travel further into caves and to explore more delicate environments.
Military divers: Military divers often need to be able to operate in stealth mode. Rebreathers can allow military divers to approach their targets without being detected.
Underwater photographers: Underwater photographers often need to be able to spend long periods of time underwater without disturbing the environment. Rebreathers can allow underwater photographers to capture images of marine life that would not be possible with traditional open-circuit scuba gear.
## Conclusion
Rebreathers are a specialized piece of scuba diving equipment that can offer significant advantages over traditional open-circuit gear. However, they are also more complex and expensive to operate, and they require specialized training to use safely.
Divers who are considering using a rebreather should carefully weigh the advantages and disadvantages before making a decision.