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Passing Decom Time

Discussion in 'Commercial Divers' started by Akimbo, Jul 3, 2010.

  1. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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  2. sterlingMarineService

    sterlingMarineService Barracuda

    # of Dives: 25 - 49
    Location: Seattle Washington, USA
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    cool. I have hear of people bringing their iphones under with them for deco time
     
  3. chrisski

    chrisski Angel Fish

    # of Dives: 500 - 999
    Location: Oley, PA
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    i thought no electronics, etc for surface deco,
     
  4. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    Sur-D O2 is fine as long as the electronics is inside housing at one atmosphere. It would not function in an HeO2 chamber since the Helium would leak in and destroy the display and maybe even the batteries.
     
  5. chrisski

    chrisski Angel Fish

    # of Dives: 500 - 999
    Location: Oley, PA
    54
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    how about fire
    thought that was point of no synthetics etc
     
  6. super7

    super7 Regular of the Pub

    # of Dives: 50 - 99
    Location: TYO, JPN
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    First, I didn't understand how an inactive gas can destroy LCDs and batteries, since I was thinking chemical-reaction-wise.
    I'm guessing you're implying that helium can seep in through the seals adding pressure inside the housing, which is understandable to me. Then, the added pressure may destroy the LCDs and possibly batteries. Am I right?
     
  7. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    Inert gas that is not the problem, pressure differential on compression and decompression is. Helium is only a problem because of its permeability rate through transparent materials. Chemically, some batteries outgas compounds that are not absorbed by Pura-Fil or activated charcoal and can't be analyzed without a mass spec or gas chromatograph -- rarely available offshore. The batteries and electronics work fine in a housing for extended periods in N2O2 sat runs.

    I know that many if not all liquid crystal displays fail after one or two cycles, I have not tested LCDs but I suspect they will also. Helium leak rates are actually faster through transparent materials than past the seals themselves in most configurations, thus the reason for Helium relief valves on mechanical watches.

    http://www.scubaboard.com/forums/5352815-post44.html
     
  8. chrisski

    chrisski Angel Fish

    # of Dives: 500 - 999
    Location: Oley, PA
    54
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    i was referring t the O part of the mixture and potentially flammable electronics (minute spark?) but if it works..... who am I to judge
    school also said my contacts would bond to my eyes welding, per my eye doc., b.s.
     
  9. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    You are correct regarding electrical devices that are not protected inside a one-atmosphere housing. Housings are effective in N2O2 environments because the Oxygen permeability rate through transparent materials is virtually, if not actually, zero. There are probably some diving supervisors that would not be comfortable letting one in the barrel though.

    Ambient O2 levels never get very high except in one of those transparent one-person hospital torpedo chambers anyway. You have to keep the O2 level low in a multi-person chamber for the off-O2 periods in the tables, fire/explosion, for medical assistants, and in case of O2 toxicity so you can pull the BIBS (Built-In Breathing System) mask — basically an oral-nasal mask with a demand regulator for treatment gases or emergency breathing.

    That is not to imply that O2 safety procedures are not critically important, just that the fire/explosion risk in a treatment chamber is not as extreme as a pressurized pure O2 environment.

    Sorry for skipping over your first post, just didn’t register the first time.
     
  10. chrisski

    chrisski Angel Fish

    # of Dives: 500 - 999
    Location: Oley, PA
    54
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    roger, I'm up to speed on bibs , no problem for skip over i was only concerned for your health and turning the pot into a bomb enjoy your reading! school was really 1970s on everything so your probably fine and technology is wonderful.
     

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