rebreathers?

[ScubaDuba723]

Ok sorry but I am very new to diving but am addicted but I am still not sure what rebreathers do? Can anyone explain what they are used for? is it like another tank?

 

[Doc]

I like them because they are quite silent.

You can really sneak up on critters very closely. The difference is amazing without the noise of exhaust bubbles.

 

[battles2a5]

Rebreathers or "closed circuit" use a breathing loop instead of exhaling inhaled gas into the water (open cicuit). The benefits vary between fully closed and semi-closed rebreathers. Semi-closed rebreathers (SCR) are essentially gas extenders. A large portion of the breathing gas is recycled through the breathing loop and scrubbed of CO2, while a small portion of the gas is refreshed to replenish the oxygen that was metabolized from the loop. SCRs use a single gas to accomplish this. So the main benefit here is more bottom time w/ less gas. A fully-closed unit (CCR) constantly recycles the same volume of gas and both scrubs the CO2 and replenishes the oxygen. The CCR uses pure oxygen to replenish the loop and a diluent gas to serve as the base for the loop. CCRs extend gas efficiency to a greater extent than SCRs. The greater advantage is that since the unit replenishes the oxygen directly it can maintain a constant PO2 throughout the dive, so you are always breathing the optimal gas mix throughout the dive and decompression is optimized. So the breather is not gas constrained and allows deeper/longer dives to accomplished with optimized deco profiles. Hope this helps! Check out wikipedia or howstuffworks.com for more detailed descriptions

 

[mood]

From the Encyclopedia of Recreational Diving:

Open circuit.
When you inhale, you breathe in from a compressed gas cylinder. When you exhale, your breath vents into the water and bubbles to the surface.

Closed-Circuit Rebreathers (CCRs).
When you inhale, you breathe in from a bag (counterlung). When you exhale, your breath cycles through a system that removes waste carbon dioxide and replaces consumed oxygen, then returns it to the counterlung. There are no bubbles.

Semi-Closed Rebreathers (SCRs).
When you inhale, you breathe in from a counterlung. When you exhale, your breath cycles through a system that removes waste carbon dioxide and returns it to the counterlung. It replaces consumed oxygen by employing a slow, steady flow of gas into the counterlung, resulting in a slow, small stream
of bubbles.

 

[ScubaDuba723]

Oh my god this is brilliant are CCRs very expensive? Because I want one!!!!

 

[Cave Diver]

Oh my god this is brilliant are CCRs very expensive? Because I want one!!!!

There are numerous models on the market with more on the way. They actual cost of one is dependent on the rig you get and the bells and whistles you choose to go with it. The range is around about $6k to over $15k depending on what you choose, not including training.

eCCR (electronically controlled) tend to be more expensive due to the addition of electronics.

mCCR (mechanically controlled) tend to be a little cheaper.

Maintenance on them tends to be a bit more critical and sometimes more time consuming than OC.

They also need specific training on the unit you choose to operate them proficiently, which can be rather expensive. Expect to spend between $1k-2k on it.

Many CCR divers choose to carry bailout, which is basically a SCUBA tank and reg so they can switch to OC if they have a problem with the rig, so you still need to have some basic gear.

Although some people do go almost straight to CCR when they start diving, its somewhat rare. A lot of people advocate that you be proficient in OC diving first, because if you do have to bailout you dont want to be struggling with your OC skills at such a critical time.

 

[Gene_Hobbs]

If you are looking for more to read, this is a good proceedings to skim through:

Richardson, D; Menduno, M; Shreeves, K. (eds.) 1996. Proceedings of Rebreather Forum 2.0. Diving Science and Technology, Santa Ana, CA. RRR ID: 7555

but there is a lot more where this came from.



Find us on Facebook to discover more about the Rubicon Foundation. While you are there become a fan of Rubicon.

 

[Cave Diver]

Gene I just wanted to take a moment and say hello. We spoke briefly at JB last Oct, but I didn't realize that was you at the time. You were there with 4 Meg divers and I my buddy and I were the other two Meg divers.

I was helping an OC diver sort out some gear issues...

It was good to meet you in person and put a face to the name!

 

[HowardE]

Oh my god this is brilliant are CCRs very expensive? Because I want one!!!!

It is brilliant. Actually - Rebreathers pre-date Open Circuit Scuba by quite a bit. The first successful rebreather dive was in 1878!

However, like others have said... Rebreathers are more expensive than OC Scuba, and the training, equipment, and maintenance requires more commitment than OC scuba as well.

ScubaBoard has a rebreather forum here -> http://www.scubaboard.com/forums/rebreathers/

we have a lot of rebreather experts on board, including John Chatterton, Jill Heinerth, and Richie Kohler - to name a few.