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Thread: What if No O2 available?

  1. #1
    RBW Member Toman is an unknown quantity at this point Toman's Avatar
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    What if No O2 available?

    Hi,

    I woke up this morning wondering a new, probably silly, question:

    Have you experienced while traveling without your own tanks places where you could not get pure O2 for your rebreather but let's say only 40 or 50% Nitrox?

    In that case, did you use a non 100% O2 tank instead? And how low in the percentage of O2 did you go?

    Cheers
    Thomas

  2. #2
    Down to no good kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter has a reputation beyond repute kwinter's Avatar
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    JJ, Flex

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    Re: What if No O2 available?

    Maybe other RBs are different, but for me the problem would be how to calibrate. The Optima only calibrates on 100% O2.

  3. #3
    San Diego rEvo Mafia "The Brandon" has a spectacular aura about "The Brandon" has a spectacular aura about "The Brandon" has a spectacular aura about "The Brandon" has a spectacular aura about "The Brandon" has a spectacular aura about "The Brandon" has a spectacular aura about "The Brandon"'s Avatar
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    Re: What if No O2 available?

    I ran low on O2 last week after a dive and really wanted to go on a 2nd. I ran offboard 60% instead of O2 for a simple little 100' dive and did just fine. With the 60% deeper woud have been better.

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    RBW Member Kermit has a spectacular aura about Kermit has a spectacular aura about Kermit has a spectacular aura about Kermit has a spectacular aura about Kermit has a spectacular aura about Kermit has a spectacular aura about Kermit's Avatar
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    Submatix mCCR

    Re: What if No O2 available?

    You guys must be running SCR, right?

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    So many CCR So little etc Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase has a reputation beyond repute Mark Chase's Avatar
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    Re: What if No O2 available?

    So long as narcosis isnt an issue you could prety much run the unit off anything over 50% (below 50 it gets a bit daft unless your deep and if your deep theres the narcosis issue


    Personaly Id whack 100% in to any old cylinder.

    ATB

    Mark

  6. #6
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: What if No O2 available?

    Quote Originally Posted by Mark Chase  View Original Post
    So long as narcosis isnt an issue you could prety much run the unit off anything over 50% (below 50 it gets a bit daft unless your deep and if your deep theres the narcosis issue


    Personaly Id whack 100% in to any old cylinder.

    ATB

    Mark
    Please explain how the narcosis issue is any different than when using pure O2?
    Cheers,

    Dave....

    www.wedivebc.com

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    Re: What if No O2 available?

    Quote Originally Posted by wedivebc  View Original Post
    Please explain how the narcosis issue is any different than when using pure O2?


    If your injecting 50% nitrogen into the mix insted of pure 02 you will be injecting twice as much 50% to get to the same level as you would using 100% and in doing so diluting what ever the diluient is with the inert Nitrogen. The inert wouldent be there if you were using 100% so it would never have been injected.

    Not a problem if your diving air, but it is if your on something like 18/45. You will replace the helium in the loop with nitrogen.

    Not good for narcoisis




    ATB

    Mark

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    Re: What if No O2 available?

    Quote Originally Posted by kwinter  View Original Post
    Maybe other RBs are different, but for me the problem would be how to calibrate. The Optima only calibrates on 100% O2.


    Calibrate it before you go away on holiday and dont touch it again till you get home.


    Thats what I did.


    Just pray you dont have a cell error in the middle of the trip.


    This "safety feeture" on the Hammer Head is a problem. It wont even calibrate high 02 contents. It dosent make it a travel freindly system.

    ATB

    Mark

  9. #9
    So Cal Tech Diver aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie has a reputation beyond repute aainslie's Avatar
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    Re: What if No O2 available?

    Will someone please point out why this thread isn't very wise?

    Brandon, did you not notice a tendency for gas to build up in your loop during that dive? Either that or you must be losing a lot of gas in your system. Ask yourself why one of these two things would be necessary. And think carefully before advising others to do this.

    This is a pretty dangerous idea. At the very least you should realize that there will be a pressure build-up that will need regular releasing. It makes a joke of calibration, and it will mess with most eCCR's, and require a LOT of manual addition in an mCCR.

    I wouldn't do it.
    Last edited by aainslie; 6th November 2008 at 13:59.
    Andrew Ainslie

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  10. #10
    Dave Tomblin wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc has a reputation beyond repute wedivebc's Avatar
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    Re: What if No O2 available?

    Quote Originally Posted by Mark Chase  View Original Post
    If your injecting 50% nitrogen into the mix insted of pure 02 you will be injecting twice as much 50% to get to the same level as you would using 100% and in doing so diluting what ever the diluient is with the inert Nitrogen. The inert wouldent be there if you were using 100% so it would never have been injected.

    Not a problem if your diving air, but it is if your on something like 18/45. You will replace the helium in the loop with nitrogen.

    Not good for narcoisis




    ATB

    Mark
    Since the OP didn't mention trimix in his post why obfuscate the issue with this?
    If using air dliuent it doesn't matter which tank the nitrogen comes from, the effect on narcosis is the same.
    Cheers,

    Dave....

    www.wedivebc.com

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