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andrespp

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I didn't say I went from 1.3 to hypoxic. I went from normoxic to hypoxic in 90 seconds. There is a difference.

The only reason that I can think of for diving a CCR with a normoxic gas is during air breaks on very long decos. And anyway, the diver doing so should be very on top of his/her ppO2, even more considering that it is a mCCR.
 

stuartv

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The only reason that I can think of for diving a CCR with a normoxic gas is during air breaks on very long decos. And anyway, the diver doing so should be very on top of his/her ppO2, even more considering that it is a mCCR.

What percentage of CCR divers do you reckon are actually trained to be able to use a hypoxic dil (as I presume you are suggesting)?
 

andrespp

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What percentage of CCR divers do you reckon are actually trained to be able to use a hypoxic dil (as I presume you are suggesting)?

The assumption you are making is wrong....a normoxic mix can be obtained in the loop using non hypoxic dil. Second, I do not see how your question is related to the discussion.
 

tbone1004

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The only reason that I can think of for diving a CCR with a normoxic gas is during air breaks on very long decos. And anyway, the diver doing so should be very on top of his/her ppO2, even more considering that it is a mCCR.

I don't know many people that use the CCR for air breaks because of the nuisance of stabilizing the whole loop back. They will either kick over to an OC regulator or they will let the ppO2 decay down naturally as your body is offgasing and then O2 flush it back up.
 

stuartv

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The assumption you are making is wrong....a normoxic mix can be obtained in the loop using non hypoxic dil. Second, I do not see how your question is related to the discussion.

You said this:

The only reason that I can think of for diving a CCR with a normoxic gas is ...

"Normoxic gas" is anything with 16% - 21% O2, right?

So, the only way I am able to interpret your statement is "the only reason for diving a CCR with a dil that has 16% - 21% O2 is ...".

On further thought, I think you are talking about the inspired ppO2 and making the distinction that the diver should be breathing a hyperoxic mix (i.e. a mix with a ppO2 greater than 0.21). Correct?

My impression was that nadwidny was not making that distinction. He was simply saying that the loop can go from non-hypoxic to hypoxic quickly.
 

nadwidny

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And anyway, the diver doing so should be very on top of his/her ppO2, even more considering that it is a mCCR.
Yup. In a perfect world that would work. Until it doesn't. As I found out.
 

andrespp

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On further thought, I think you are talking about the inspired ppO2 and making the distinction that the diver should be breathing a hyperoxic mix (i.e. a mix with a ppO2 greater than 0.21). Correct?

That´s it.
 

andrespp

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Yup. In a perfect world that would work. Until it doesn't. As I found out.

I do not know what kind of ccr you use, but with a mccr you need to both monitor frequently your ppO2 especially when close to surface and have a mix rich in oxygen on the shallows. If the pasive orifice clogs and you fail to monitor your ppo2 for such amount of time, is an human error on top of a mechanical issue.
 

andrespp

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I don't know many people that use the CCR for air breaks because of the nuisance of stabilizing the whole loop back. They will either kick over to an OC regulator or they will let the ppO2 decay down naturally as your body is offgasing and then O2 flush it back up.

Nuisance? Flushing the loop out once or maybe twice is a nuisance? Really?
 

Wibble

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I wrote my own pre jump check list and have it on whiter electrical tape on my handset. I have been using it for several years now and have only found need to modify one word and add one new line. It may not be 100% comprehensive but it certainly covers the critical points to keep me alive, everything else can be dealt with easily underwater.
Seems an excellent idea.
Any chance of a photo?
 
https://www.shearwater.com/products/perdix-ai/

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