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Dive Tables and Equivalent Air Depth

Dive Tables and Equivalent Air Depth. Introduction. Recommended Nitrox Dive Tables Equivalent Air Depth metres sea water ( msw ) Use of EAD & Tables Air Tables & computers Nitrox computers. Nitrox Tables. Buehlmann Tables Definitions Use – as air tables Specific Nitrox Tables:

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Dive Tables and Equivalent Air Depth

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  1. Dive Tables and Equivalent Air Depth

  2. Introduction • Recommended Nitrox Dive Tables • Equivalent Air Depth metres sea water (msw) • Use of EAD & Tables • Air Tables & computers • Nitrox computers

  3. Nitrox Tables • Buehlmann Tables • Definitions • Use – as air tables • Specific Nitrox Tables: • EAN28 • EAN32 • EAN36 • EAN40 • See Appendix 2

  4. Nitrox Tables • Extra Rule • when moving from one mix to another the RNT is calculated using the table of new mix to be used • Longer RNT • Rule applies from any mix (EANx or air) to any other mix (EANx or air)

  5. Equivalent Air Depth • Nitrox – ppO2 > ppO2 Air • Nitrox –ppN2 < ppN2 Air • Depth where EAN ppN2 equivalent to air • Depth where ppN2 of Nitrox = ppN2 of Air • Known as EAD

  6. EAD - example Example: EAN36: ppN2 = 0.64 bar At 25m = 3.5 Bar (absolute) x 0.64 = 2.24 bar ppN2 Air: ppN2 = 0.79 bar Depth using air at which ppN2 = 2.24 bar 2.24 / 0.79 = 2.83 Bar or 18.3m The equivalent air depth using EAN36 at 25m is 18.3m

  7. EAD • Used for any mix • Given depth • Determine no-stop times • EAD 18.3m - use air tables • Calculated in two ways: • Use EAD formula • Use EAD table (Appendix 3)

  8. EAD Formula EAD (Bar) = FN2 in mix x P / 0.79 (FN2 in air) FN2 = decimal fraction of nitrogen P = pressure of dive (absolute) EAD in bar – convert to metres for equivalent depth in msw

  9. Example: Using Nitrox 32% at 33 metres. Go across to reach 32%. Go down to 33 metres. Follow the row across to the left, where the E.A.D. can be read: 27 metres.

  10. Using EAD and Air Tables • Use EAD with any Buehlmann Air table • Determine no-stop time • Care not to exceed depth • Used for repetitive dives • Keep within no-stop times • Extra benefit of nitrox over air on safety stop

  11. Air Tables & Computers • Nitrox mix with standard tables or computer • Advantage • Reduces risk DCI • MOD (max ppO2 1.4) • CNS% • No-stop times

  12. Nitrox Computers • Use specific nitrox computer • Specify mix used prior to every dive • Include in buddy check • Track oxygen • Track nitrogen • CNS% • No safety advantage • Pre-selected % safety margin built in latest models • Multi-level diving • Always follow manufacturer’s recommendations

  13. Summary • Nitrox Dive Tables • EAD concept and use • Air Tables and computers • Nitrox computers • Safer options • Plan the dive and dive the plan

  14. Questions?

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