Rebreathers have been growing in popularity in the last few years with recreational divers. Scuba rebreathers are not new, they were created by Cousteau back in 1944. Rebreathers are commonly used by technical divers and military divers. So how long do scuba rebreathers last?
The answer to the question depends on the size of the cylinders. For example, a 2-liter tank at 200 bar pressure contains enough oxygen for around 4 to 6 hours dive. There are a number of factors that can affect how long a rebreather can last such as the capacity of the tank, chemicals/gas used, depth of dive, time at various depths, and rate of gas used.
In today’s post, we will go through in more detail how long do rebreathers last, so let’s get started!
Read more on common questions asked by divers
What Is A Scuba Rebreather?
A rebreather is a closed-circuit system, as opposed to a standard open-circuit scuba system that most recreational scuba divers use. The simplest explanation is that a rebreather allows the diver to breathe their own air over and over again. It is claimed that human lungs absorb only 5 percent of the oxygen present in the air, where normally there is 21% O2 in the air. So the rebreather will recycle the exhaled air so it can be used over and over again.
With rebreathers being a closed-circuit breathing system it does not expel air into the water. Generally, a rebreather will have two cylinders, one will be filled with pure oxygen and the other a diluent which is a mix of air, helium, nitrogen, and so on. Simply the diluent is for keeping the volume of the system constant when descending.
While the oxygen is used in a similar way as the diluent cylinder but is also added when the oxygen is consumed and converted to carbon dioxide. With the carbon dioxide absorbed by the filter and so its volume becomes unimportant.
There are a number of pros and cons with the rebreather. These are as follows.
The Pros
- You can diver for longer and deeper.
- The size and weight of a rebreather are more compact than the standard open circuit diving tanks.
- There are no bubbles so it can be easier to get close to the marine life.
The Cons
- Rebreathers are expensive. It is a very specialized apparatus so you can expect to pay anywhere upwards of $10k.
- It is a specialized apparatus so you will have to learn how to use it.
- They are more comprehensive pre and post-dive assembly and disassembly steps when compared to the standard diving tanks.
How Long Do Rebreathers Last?
The answer to the question depends on the size of the cylinders. For example, a 2-liter tank at 200 bar pressure contains enough oxygen for a dive of between 4 to 6 hours dive. There are a number of other factors that can affect how long a rebreather can last such as depth of dive, time at various depths, and rate of gases used.
There are a number of limitations, these are as follows.
- Scrubber – The scrubber containers size is a limiting factor for your dive. At a certain point, the scrubber will stop absorbing CO2, and oxygen supply, which is there is a limited supply. There is also the extra load and stress means more CO2 is expelled, which can shorten your scrubber life faster.
- Bailout – The is also the chance rebreather could fail during the dive and the scuba diver will need a backup rebreather.
Do Rebreathers Run Out Of Air?
The rebreathers do not run out of air, but they will run out of oxygen eventually.
Do Rebreathers Make Bubbles?
Rebreathers produce few to no bubbles. This is one of the reasons why the military uses rebreathers other than the fact that they can dive for longer.
How Do You Become A Rebreather Diver?
PADI has a course to teach scuba divers how to use the rebreathers. The PADI Rebreather Diver course introduces the diver to the rebreather and also the pre-post diving procedures and disassembly and assembly.
There are prerequisites to doing the PADI rebreather diver course, these are as follows.
- Most have the PADI Open Water Diver vert completed.
- Most have the PADI Enriched Air Diver completed.
- Need to have 25 or more logged dives.
Wrapping Up
Finally, there are a number of factors that can affect how long a rebreather can last such as the capacity of the tank, depth of dive, time at various depths, and so on. How long a rebreather can last can vary but you should expect a 2-liter tank at 200 bar pressure to last around 4 to 6 hours during your dive.
And that’s it for now! I’d love to know if this guide on how long do rebreathers last has helped you. Let me know if you have any questions and let me know if there is more to add.
