CCR vs SCR

[rigdiver]

SCR=gas extender
VS
CCR=gas miser

 

[Rhone Man]

48 hours!!!!!!!!

You must mean 4 - 8 hours...

Is he talking about 1 CCR or more???

Note to the other RB divers....

A scrubber that last 48 hours???? Is that a Holy Grail or What!!!!!

He definitely says 48 (see pages 173 and 174). He talks about a diver named Bill Stone spending 24 hours underwater at Wakulla Spring using a MK-1 rebreather, and "calculations of his remaining consumables showed that he could have stayed another 24 hours. His biggest problem during the test dive was boredom."

Don't know much about rebreathers, but that is what he says.

 

[PerroneFord]

He definitely says 48 (see pages 173 and 174). He talks about a diver named Bill Stone spending 24 hours underwater at Wakulla Spring using a MK-1 rebreather, and "calculations of his remaining consumables showed that he could have stayed another 24 hours. His biggest problem during the test dive was boredom."

I know people who were there for that dive (and have heard them talk about it) Boredom was NOT his biggest problem!

I would also say in regards to SCR, that there is nothing that says that SCRs can only use one gas. Though they cannot mix on the fly like CCRs, you can have them draw from more than one tank with a switch block, depending on the SCR. This allows gas extension of any mix you choose to carry with you. Whether that be 32%, 10/70, or 50%, etc.

So while you still have to carry multiple tanks, they need not be as large as the tanks you take for OW diving.

To me, the great benefit to SCR, is that you remove the reliance on electronics to mix and monitor your gas. When you plug in a tank of 32%, you're getting 32%, assuming all is well with the unit.

SCR isn't as "sexy" as CCR, but I prefer the simplicity.


Don't know much about rebreathers, but that is what he says.[/QUOTE]

 

[wedivebc]

When you plug in a tank of 32%, you're getting 32%, assuming all is well with the unit.

Actually not correct. You have to allow for metabolized O2 and you will end up with something less than 32% depending on metabolic rate.

 

[Mr.X]

He definitely says 48 (see pages 173 and 174). He talks about a diver named Bill Stone spending 24 hours underwater at Wakulla Spring using a MK-1 rebreather, and "calculations of his remaining consumables showed that he could have stayed another 24 hours. His biggest problem during the test dive was boredom."

Don't know much about rebreathers, but that is what he says.

Wes Skiles and B. Stone were testing early prototypes for what eventually became the Cis Lunar MK 5p rebreather. I believe the tests were conducted very, very shallow. Also, they had gigantic scrubbers and tons of gas/personnel to support that test.

In warmer waters (like Mexican cenotes) some rebreather scrubbers can last a fair number of hours beyond what is typically stated, though for liability purposes no manufacturer would ever state that up front.

X

 

[PerroneFord]

Actually not correct. You have to allow for metabolized O2 and you will end up with something less than 32% depending on metabolic rate.

Yes, I know, but in a non-technical discussion I was trying to avoid going there.


...the politics of the bag as it were.

 

[rjack321]

CCR on the other hand I consider as "blending on the fly". You are basically always diving the "best" mix for the given depth which minimizes your decompression obligation.

Or minimizes some other limit like max ppO2, CNS, or pulmonary toxicity.

CCRs, even mCCRs, absolutely require electronics and rather iffy O2 sensors in a high pressure, high moisture environment to run/operate.
SCRs can be run without any O2 sensors, some units being more suited for this that others.

 

[scubanimal]

As one who also started on a SCR (Dolphin) and has moved onto CCRs, I am not as inclined to blanket recommend that folks go direct to CCR. I think that most of us on CCR are very comfortable doing deco dives, and a fair amount of us dive beyond rec limits. But, that does not mean everyone wants to. I truly enjoyed the simplicity of the dolphin and occasionally miss it for my routine dives locally that are in the 60-100' range where I'm limited to no-deco dives.

If someone plans to move on to Deep & Deco, yes the CCR is better tool, but depending on the model CCR chosen a SCR could be a nice half-way step in the learning process. And while I'm not a fan of buying a SCR off of e-bay, they are in fact readily available and considerably easier on the pocket book to start. Plus, depending on the area, it may be easier to get Nitrox then pure O2. Plus a lot cheaper to get trained on.

So while I agree most SCR divers do move on to CCRs, and that a large percentage of current CCR divers could have started with a CCR instead of a SCR first, I'm not convinced that going straight to CCRs is the right thing for everyone.

Just a little perspective.

 

[Atomic_Diver]

How old do you have to be to learn how to dive the CCR Inspiration/Evolution Air Dilute?

 

[BlueFrog]

I believe that its 18 years old and 100+ logged dives however I don't think age should be the only consideration. In my opinion, diving experience and commitment are way more important.

Not that I know any 18 year olds with $10,000. laying around plus money for consumables.