+ Reply to Thread
Page 4 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 31 to 40 of 48

Thread: Two C02 hits - time to get fit?

  1. #31
    RBW Member delta-v is an unknown quantity at this point delta-v's Avatar
    Join Date
    Apr 2012
    Location
    UAE
    Posts
    21
    Inspiration Vision

    Re: Two C02 hits - time to get fit?

    Another interesting aspect I hadn't considered emerged when I was discussing these hits with a very senior instructor that I have the pleasure of knowing.

    On both these occasions I was diving MLV (min. loop vol.) and so CO2 retention within the unit can be ruled out. However, when I visualise my breathing pattern under MLV, it's clear that I'm not using my entire lung capacity - quite simply I don't need to. As such, it's very possible that CO2 is being retained - akin to shallow breathing.

    Under normal circumstances this wouldn't be a problem, but under conditions of heavy exertion the retention could become a problem.

    I will explore this angle on my next dive. It fits in with the retention theory that PSotis has kindly shared on this topic.
    Last edited by delta-v; 23rd December 2014 at 20:11. Reason: typo

  2. #32
    RBW Member delta-v is an unknown quantity at this point delta-v's Avatar
    Join Date
    Apr 2012
    Location
    UAE
    Posts
    21
    Inspiration Vision

    Re: Two C02 hits - time to get fit?

    Quote Originally Posted by PSotis  View Original Post
    I don't have all the facts of your story, but you do paint a clear picture. There is a common misperception that you can over-breathe a scrubber. On some units that is possible, but on your unit that is unlikely.
    I'm sure you know what you're talking about, but intuitively this doesn't make sense to my layman understanding : )

    Surely there's an upper limit to volumetric gas flow through the scrubber beyond which the gas stream is moving too fast for any useful CO2 extraction to take place? This is what I meant by "overwhelming the scrubber".

    Are you saying that breaching this limit is not possible on a properly packed Inspiration 2.5kg scrubber under diving conditions? Just trying to understand the dynamics involved, thanks!
    Last edited by delta-v; 23rd December 2014 at 20:25. Reason: additional info

  3. #33
    RBW Member Larry0428 is on a distinguished road Larry0428 is on a distinguished road Larry0428's Avatar
    Join Date
    Jun 2012
    Location
    Australia
    Posts
    67
    Inspiration Vision

    Re: Two C02 hits - time to get fit?

    Quote Originally Posted by mdma946552  View Original Post
    great so i need o2 lube only on the o2 first stage that's good news thanks
    Hi mdma946552
    Just to be clear I said I use it on the low pressure components only (eg loop hoses, scrubber O ring, Lid O ring). I do not use it on high or medium pressure components (eg first stage, O2 SPG and hoses, solenoid hose, O2 Mav and hoses etc), on these components I only use O2 grease.

    Attached below is the note I saw from Martin Parker FYI:
    Something lost in translation I’m afraid J


    Christalube is an excellent O2 compatible grease. It’s a bit expensive and possibly is used too sparingly on a large scrubber O ring.



    In the scrubber cartridge application and on all Low pressure (ambient pressure) loop O rings - Silicone grease lasts longer, allows the assembly to slide nicely and never leaves hard deposits on the components – which can happen with some O2 compatible greases.



    If you don’t lubricate the scrubber cartridge O ring you will get small levels of CO2 past which will be detected by the CO2 sensor.





    From an advice point of view – it’s easier to advise using O2 compatible grease on everything – then there’s no chance of a mix up - the cost of a mix up being potentially horrific. But there are some applications where the silicone grease is better ( the scrubber cartridge being one). Please note: never use silicone grease on any Medium or High Pressure O2 components.



    On the large scrubber O rings: With all O2 compatible greases that I have tried, you will need to clean off and re-lubricate more often than you would using silicone grease.



    Kind regards,



    Martin Parker

    Managing Director

    AP Diving





    W: www.apdiving.com

    E: martinparker@apdiving.com

    T: +44 (0)1326 563834 / 561040

    F: +44 (0)1326 565945 / 573605



    Sent from my iPad using Tapatalk HD

  4. #34
    RBW Member catalina_mike is an unknown quantity at this point catalina_mike's Avatar
    Join Date
    Apr 2006
    Location
    Visalia, CA
    Posts
    109
    Evolution+

    Classic Inspo

    Re: Two C02 hits - time to get fit?

    I would not use excessive pressure when checking the check valves. That is not how it will be in the water... I create slight pressure then listen and use your eye. Your eye is very sensitive to air flow. High pressure tests could be sealing fine but normal breathing and pressure is much different. Two simple pieces of material are very important. My two cents worth...

  5. #35
    RBW Member mdma946552 is an unknown quantity at this point mdma946552's Avatar
    Join Date
    Mar 2013
    Location
    thailand
    Posts
    82
    inspo clasic

    Re: Two C02 hits - time to get fit?

    got it

  6. #36
    RBW Member Marbry is an unknown quantity at this point Marbry's Avatar
    Join Date
    Sep 2008
    Location
    Tennessee
    Posts
    59
    Revo

    Re: Two C02 hits - time to get fit?

    I've experienced high CO2 on open circuit before, to the point of feeling suffocated. This was when under heavy exertion attempting to move some well entrenched rocks.

    But it took a lot of work to get there.

  7. #37
    RBW Member delta-v is an unknown quantity at this point delta-v's Avatar
    Join Date
    Apr 2012
    Location
    UAE
    Posts
    21
    Inspiration Vision

    Re: Two C02 hits - time to get fit?

    Quote Originally Posted by catalina_mike  View Original Post
    I would not use excessive pressure when checking the check valves. That is not how it will be in the water... I create slight pressure then listen and use your eye. Your eye is very sensitive to air flow. High pressure tests could be sealing fine but normal breathing and pressure is much different. Two simple pieces of material are very important. My two cents worth...

    Not using excessive vacuum/pressure makes sense, thanks. But I'm not sure how to use my eye. Could you please give a step-by-step description of your method?

  8. #38
    Owner
    PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis is a jewel in the rough PSotis's Avatar
    Join Date
    Sep 2007
    Location
    Delray Beach, FL
    Posts
    232
    Revo,Optima, Prism, Meg, Pos 7

    Kiss,Evo, Sentinel,Pathfinder,

    Re: Two C02 hits - time to get fit?

    Over breathing the scrubber makes intuitive sense to most anyone. Since the scrubber requires a certain amount of dwell time to sufficiently scrub the gas, it makes sense that breathing faster will accelerate that process and overcome the scrubber.

    I was trained that way years ago and even trained many people with that concept in my earlier years as an instructor. However, it turns out that like most things, our intuitive sense was not truly accurate.

    To be fair there are some units(and I will not name them) that are so inefficient that you can over-breathe their scrubber capacity. But your unit is not one of those models, based on my understanding.

    What changed my mind about over-breathing was when I was exposed to CE tests and variations of CE testing on ANSTI machines. Essentially these tests made me rethink two theories I held near and dear at the time. They showed me that no scrubber needed warming, so pre-breathing was not needed to initiate the reaction of the scrubber. Which is not to say there are not other excellent reasons to pre-breathe, because there are. It also showed me that CE testing far exceeds the capacity of most any human being for any length of time.

    In other words, on a descent rebreather, your body will retain CO2 and develop issues long before you over come the capacity of the scrubber. This is my understanding and it was brought to my attention by people that could show me data to support this theory, instead of using intuitive thought to reach conclusions.

    I like the way you are searching for the truth and asking questions with an open mind. Don't lose that as you learn more. Be ready to change your thinking at any time as there is always so much more to learn. Be careful of all of the old myth's that surround rebreathers...there are too many of them.



    Quote Originally Posted by sierra  View Original Post
    I'm sure you know what you're talking about, but intuitively this doesn't make sense to my layman understanding : )

    Surely there's an upper limit to volumetric gas flow through the scrubber beyond which the gas stream is moving too fast for any useful CO2 extraction to take place? This is what I meant by "overwhelming the scrubber".

    Are you saying that breaching this limit is not possible on a properly packed Inspiration 2.5kg scrubber under diving conditions? Just trying to understand the dynamics involved, thanks!
    Last edited by PSotis; 24th December 2014 at 08:01.

  9. #39
    not RBW staff. EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT has a reputation beyond repute EBT's Avatar
    Join Date
    Feb 2005
    Location
    UK, Brighton
    Posts
    2,720
    Classic Kiss

    Sports kiss, dolphin

    Re: Two C02 hits - time to get fit?

    Me and a buddy used to regularly get co2 hits when diving oc and lobstering, then swimming back against the tide. No rebreathers involved, just two idiots trying to save gas and working too hard.

    When I moved to ccr, i was told to be careful in assembly/testing of the rig and not to work too hard. That was old teaching, but it was right and still holds true in all rebreathers.

    Nowadays Im old and still remind myself to "let my breathing rate dictate my work rate, not the other way around".

  10. #40
    Jst anothr Breather Diver Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius is a splendid one to behold Nitrogenius's Avatar
    Join Date
    Jan 2010
    Location
    Germany
    Posts
    1,148
    rEvo III rms

    Inspo HH + classic Dolphin Ray

    Re: Two C02 hits - time to get fit?

    Quote Originally Posted by EBT  View Original Post
    "let my breathing rate dictate my work rate, not the other way around".
    Awesome !!

+ Reply to Thread
Page 4 of 5 FirstFirst 1 2 3 4 5 LastLast

Posting Permissions

  • You may post new threads
  • You may not post replies
  • You may post attachments
  • You may not edit your posts