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Synthetic Blubber

Discussion in 'Apparel' started by Saniflush, Jun 19, 2018.

  1. kelemvor

    kelemvor Big Fleshy Monster ScubaBoard Supporter

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    I see, thanks for the explanation. Sounds great!
     
  2. giffenk

    giffenk Great White

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    Did anyone actually read the articles? They make no sense.

    The scientists put a normal wetsuit in a pressure chamber with heavy gas. That should accomplish zero. Neoprene wetsuits are closed cell. The gas current trapped in the inner bubbles is going nowhere. Nothing in, nothing out. Unless you break the bubble. And then the wetsuit is useless as it is now a sponge.

    What am I missing?
     
  3. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    Gas slowly passes through and equalizes in the closed cells of the foam Neoprene. This was discovered in the early
    experimental saturation dives. Wetsuits, hot-water heated and conventional, would compress with the divers in the chamber HeO2 environment. They would get thinner just like in the water. The suit thickness would slowly recover after a few days in the chamber. The big surprise came when they sent the suits out after the dive to make decompression more comfortable. They enlarged to about twice the size and basically exploded all the closed cells in the suit.

    Hot water suits today are permanently compressed to collapse the cells to eliminate this problem and make the suits more flexible. That is how Dick Long discovered the process used on DUI's crushed Neoprene suits.
     
    eleniel and tridacna like this.
  4. Rooster59

    Rooster59 Solo Diver

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    That's a BINGO
     
  5. WetSEAL

    WetSEAL Nassau Grouper

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    I just did the math to figure out how much positive buoyancy could potentially be shed from a 7mm wetsuit if the pores were replaced with a heavy gas like xenon instead of air. Looks like it's about 0.1 lbs best case...so not enough to make a difference.
     
  6. giffenk

    giffenk Great White

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    Location: toronto
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    So closed cell neoprene is not really "closed cell"?

    I want to believe that for most practical purposes that neoprene is truly closed cell for most of its useful life - or else it would not work. Neoprene makes a crap sponge - which it would be if the cells exploded. Or degraded with age.

    So what was their experiment? (@Akimbo explanation above slightly confuses me...) How much gas actually diffused into the closed cells? How fast? And for how long?
     
  7. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    For reference, even a Rolex Sea Dweller is not really a "closed cell". All know known transparent materials act more like filters than barriers to Helium. That is why the Helium relief valve was invented.

    Closed cell foam Neoprene is pretty effective against large molecules like water, but not many glasses.
     
    giffenk likes this.
  8. peterak

    peterak Nassau Grouper

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    Yep. Even the heaviest gas is much, much less dense than water.
     
  9. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    The experiments were to verify the safety of decompression tables for saturation diving in addition to developing all the required support systems. Typical dives would last between a week and a month. I can't say definitively how long it takes for complete equalization but 1/4" Rubatex G231n material would recover to what looked like full thickness in a couple of days.

    The suits would also decompress at least as fast as the divers. They were fine as long as they were not locked-out and brought to the surface in a few minutes.

    Think of closed cell foam Neoprene like lung tissue. Gas passes across the tissue quite rapidly while red blood cells don't.

    The biggest problem I see with the concept described in the OP is the less thermally conductive gas will leak out of the Neoprene cells pretty quickly. This is the same problem with Argon filled multi-pane windows. The great majority of Argon leaks out with virtually zero differential pressure in less than five years through a process called diffusion. In this case, most of it leaks through the edge seals much more rapidly than the glass.

    Look close enough and you will see why very few non-metallic materials have zero gas permeability. Bone is one of the slowest tissues in the body for decompression calculations. This is what healthy human bone looks like under a scanning electron microscope.

    full.jpg
     
    giffenk likes this.

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