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Thread: Extending SCR Dolphin depth limits...

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    Total NOOB trey is an unknown quantity at this point trey's Avatar
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    Extending SCR Dolphin depth limits...

    Any of you guys have any mods/flow rate charts for gasses other than supported gas through supported orifice to take the Dolphin down below 130ft in SCR mode? Curious about flow rates with other gasses (ie 28%, etc)through unsupported orifices (ie 40%, etc.) and wether or not some rates with some gases will support life above 30 ft.

    Thanks, Trey

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    Re: Extending SCR Dolphin depth limits...

    Quote Originally Posted by trey
    Any of you guys have any mods/flow rate charts for gasses other than supported gas through supported orifice to take the Dolphin down below 130ft in SCR mode? Curious about flow rates with other gasses (ie 28%, etc)through unsupported orifices (ie 40%, etc.) and wether or not some rates with some gases will support life above 30 ft.

    Thanks, Trey
    Not to sound condescending, but if you plan on taking any unit beyond its rated limits and you have to ask how to do it you shouldn't even be thinking about it..

    Realistically you nead either a) a method to switch gases into the rebreather, or do ascents and descents on oc with a different gas than thats used in the RB for the bottom.. More than one person has died on a drager going beyond the limits..
    Joe Radomski
    CCR Trimix Instructor Trainer
    ANDI Instructor Trainer Director #10

    All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

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    Re: Extending SCR Dolphin depth limits...

    you have a PM

    it is what it is ! wrong tool for the job.
    Last edited by shell-back; 9th December 2005 at 17:15.

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    RBW Member Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck is a jewel in the rough Crazyduck's Avatar
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    Re: Extending SCR Dolphin depth limits...

    Trey,
    Joe’s concern is a Very valid one. Not so long ago people were doing this and having some serious nightmares.
    The things that you have mentioned is the reason that people take the unit and convert it to a CCR. It keeps them for messing around with multiple gases, multiple orifices, switching certain gases on and off during the dive. The chance to really mess yourself over is very high. Plus, you have to remember the differences between fraction of oxygen and partial pressure and how closed circuit and semi closed handles each. Plus, this does not even cover flow rate issues and the scrubber rating.

    So scrap the SCR nightmare and then swing around to the possibility of a closed circuit dolphin. Lots of options here and a few people on the board that have done it. Plus a few people have scrubber endurance details and scrubber depths comments also.

    What I am about to say is my own opinion only.
    The closed circuit Dolphin while having all the characteristics of a closed circuit rebreather it has certain design issues and concerns. Doing such makes the unit truly experimental and possibly life threatening…

    Makes a KISS Classic look tasty.

    Hope this helps.
    Best regards, Andrew

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    Re: Extending SCR Dolphin depth limits...

    I iterate what others have said above.

    However, if you want to have a tool to learn, I have written a simple basic program to compute that when I first learn to program the Palm.

    It is available here. You have to join Yahoo since it is a Yahoo group list.

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    Total NOOB trey is an unknown quantity at this point trey's Avatar
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    Re: Extending SCR Dolphin depth limits...

    Thanks for the feedback guys. I haven't gotten the Dolphin cert yet...start IANTD class on Sunday. Just curious what it is capable of as a lower O2 content SCR...was only really considering the use of EANx24-28. Only looking to extend the range to about the 150ft mark for diving in the local lake. I have considered the CCR conversion (and am hunting/waiting for a KISS Sport). But at this point I just want to get some time on an RB, and since I have this one already, it's getting the nod. I'm sure I'll know more about what I've asked in the next few weeks...

    -T

  7. #7

    Re: Extending SCR Dolphin depth limits...

    Quote Originally Posted by Crazyduck
    Trey,
    Joe’s concern is a Very valid one. Not so long ago people were doing this and having some serious nightmares.
    The things that you have mentioned is the reason that people take the unit and convert it to a CCR. It keeps them for messing around with multiple gases, multiple orifices, switching certain gases on and off during the dive. The chance to really mess yourself over is very high. Plus, you have to remember the differences between fraction of oxygen and partial pressure and how closed circuit and semi closed handles each. Plus, this does not even cover flow rate issues and the scrubber rating.

    So scrap the SCR nightmare and then swing around to the possibility of a closed circuit dolphin. Lots of options here and a few people on the board that have done it. Plus a few people have scrubber endurance details and scrubber depths comments also.

    What I am about to say is my own opinion only.
    The closed circuit Dolphin while having all the characteristics of a closed circuit rebreather it has certain design issues and concerns. Doing such makes the unit truly experimental and possibly life threatening…

    Makes a KISS Classic look tasty.

    Hope this helps.
    Best regards, Andrew
    More than fair comment Andrew and I agree with all the points you raise; however I've been using the Dolphin in SCR set-up as a mixed-gas diving unit for the past three seasons. Reason behind it - my buddies ex-Royal Navy clearance diver's training and understanding of flow-rates/gas/PP02 issues and a more than basic understanding of open-circuit mixed gas diving. I see the Dolphin as a gas efficiency tool nothing more nothing less - I'm not precious about it either.

    The bulk of the diving I do is between 40-60m but we've have the unit down to 80m. The only addition I've made to the system is a swagelock block and hose that allows me to manually switch gas. The unit runs through both a Draeger Oxygauge and VR3 for monitoring PPO2 and deco. My buddy has adapted his for chest mounting for a caving project where the entrance is in 72m out in the Med; hopefully I'll pass more details on as we achieve our aims. Personally I wouldn't adapt a Dolphin for CCR - I'd buy a Inspo Classic/Kiss/Meg if that's what I wanted.

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    Re: Extending SCR Dolphin depth limits...

    Quote Originally Posted by trey
    Any of you guys have any mods/flow rate charts for gasses other than supported gas through supported orifice to take the Dolphin down below 130ft in SCR mode? Curious about flow rates with other gasses (ie 28%, etc)through unsupported orifices (ie 40%, etc.) and wether or not some rates with some gases will support life above 30 ft.

    Thanks, Trey
    Look here for all your Dolphin needs.

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    Re: Extending SCR Dolphin depth limits...

    Seriously though, why would you bother? There are far safer ways of doing this (CCR, OC to name but two).

    Have a look here http://www.davidteubner.com/images/SCR%20sim.xls and plug some numbers in and see what happens.

    Just because you can do something doesn't mean you should.

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    Re: Extending SCR Dolphin depth limits...

    The SCR gospel.

    Rich = high PO2, Lean = low PO2

    You can dive a rich mix with a rich jet
    You can dive a lean mix with a lean jet
    You can dive a rich mix with a lean jet
    If you dive a lean mix with a rich jet you might die.

    Dave T

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