1 / 27

Gas Management

Gas Management. Introduction. Recap – Advanced Nitrox Manual calculation prone to error Planning software Gas required = time x breathing rate x ambient pressure. Personal Gas Consumption. Surface gas consumption RMV Review personal RMV Work-rate & stress Example

margo
Download Presentation

Gas Management

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Gas Management

  2. Introduction • Recap – Advanced Nitrox • Manual calculation prone to error • Planning software • Gas required = time x breathing rate x ambient pressure

  3. Personal Gas Consumption • Surface gas consumption • RMV • Review personal RMV • Work-rate & stress • Example • Dive to 30m, RMV 16 litres/min • 4 Bar x 16 l/min = 64 l/min

  4. Rules • On dives: • Deeper than 40m • Involving decompression • Overhead environment • Rule of Thirds • Gas Reserves • Amount x 1.5 – decompression gas • Differing RMVs and Gas Supplies

  5. Gas Management - Example Dive 47m, 30 min RMV 16 l/min (Highest RMV of buddy group) Deco Gas: EAN 39 & EAN 80 • Bottom gas • 1.4 Bar/5.7 Bar = 0.2456 EAN 24 • EAD = 5.7 Bar x 0.76% N2 = 4.33 Bar ppN2 4.33 Bar ppN2/0.79% N2 = 5.48 Bar = 44.8m (45m)

  6. Gas Management - Example • Using 50/50 Tables, EAD 45m, 30 min • Mandatory Deco Stops

  7. Deep Stops • 1st Deep stop • (47m + 15m) / 2 = 31m • 2nd Deep stop • (31m + 15m) / 2 = 23m • 3rd Deep stop • 23m to 15m < 10m • 2 deep stops, 2 min each • Leave bottom at 26 min

  8. Deco Gas • EAN 39 from a depth of 31m (ppO2 1.6 bar) • EAN 80 from a depth of 9m (ppO2 1.52 bar) • Safety Margin • Decompression Software

  9. Example – Bottom Mix Descent & Bottom Phase: Gas Required = RMV at depth x Time 47m = 5.7 Bar RMV at depth = 16 x 5.7 = 91.2 l/min Gas required = 91.2 x 26 = 2371.2 litres

  10. Example – Bottom Mix Ascent on Bottom Mix: RMV at depth = RMV x Pressure Average pressure = (5.7 + 4.1)/2 = 4.9 Bar RMV at depth = 16 l/min x 4.9 Bar = 78.4 l/min Time for this ascent = 1.6 min. Gas Required = 78.4 l/min x 1.6 min = 125.44 litres

  11. Example – Bottom Mix Total Bottom Mix (EAN 24): 2,371 + 125 = 2,496 litres Rule-of-thirds Add 50% 2,496 x 1.5 = 3,744 litres If twin 10-litre cylinders, total 20 litres 3744/20 = 187 Each cylinder filled to at least 187 Bar

  12. Example – Deco Mix Ascent & Stops on EAN 39: Ascent • 4.1 Bar (31m) to 1.9 Bar (9m) • Average pressure = (4.1 + 1.9)/2 = 3 Bar • RMV at depth = 16 l/min x 3 Bar = 48 l/min • Time = 2.2 min. • Gas Required = 48 l/min x 2.2 min. = 105.6 litres

  13. Example – Deco Mix Deep Stops on EAN 39: • 31m RMV at depth = RMV x Pressure = 16 l/min x 4.1 Bar = 65.6 l/min Time at stop = 2 minutes 65.6 x 2 = 131.2 litres  • 23m RMV at depth = 16 l/min x 3.3 Bar = 52.8 l/min 52.8 x 2 min = 105.6 litres

  14. Example – Deco Mix Deco Stops on EAN 39: • 15m, 1 min RMV at depth = 16 l/min x 2.5 Bar = 40 l/min 40 x 1 min = 40 litres  • 12m, 4 min RMV at depth = 16 l/min x 2.2 Bar = 35.2 l/min 35.2 x 4 min = 140.8 litres

  15. Example – Deco Mix EAN 39 Required: 105.6 + 131.2 + 105.6 + 40 + 140.8 = 523.2 litres Rule-of-thirds: 523.2 x 1.5 = 784.8 litres (785 litres) 5-litre cylinder 785/3 = 157 Bar (Fill to capacity)

  16. Example – Deco Mix Ascent & Stops on EAN 80: Ascent • 1.9 Bar (9m) to 1 Bar (Surface) Average pressure = (1.9 + 1)/2 = 1.45 Bar RMV at depth = 16 l/min x 1.45 Bar = 23.2 l/min • Time = 0.9 min. • Gas Required = 23.2 l/min x 0.9 min. = 20.88 litres

  17. Example – Deco Mix Deco Stops on EAN 80: • 9m, 7 min RMV at depth = 16 l/min x 1.9 Bar = 30.4 l/min 30.4 x 7 min = 212.8 litres  -------------------------------------------------------------------------- • 6m, 3 min RMV at depth = 16 l/min x 1.6 Bar = 25.6 l/min 25.6 x 3 min = 76.8 litres -------------------------------------------------------------------------- • 4.5m, 21 min RMV at depth = 16 x 1.45 Bar = 23.2 l/min 23.2 x 21 min = 487.2 litres

  18. Example – Deco Mix EAN 80 Required: 20.88 + 212.8 + 76.8 + 487.2 = 797.68 litres Rule-of-thirds: 797.68 x 1.5 = 1,196.52 litres (1,197 litres) 7-litre cylinder 1197/7 = 171 Bar (Fill to capacity)

  19. Total Gas Requirements Bottom Mix: EAN 24: 3,744 litres 2 x 10-litre cylinders @ 187 bar Deco Mix: EAN 39: 785 litres 5-litre cylinder @ 157 bar EAN 80: 1,197 litres 7-litre cylinder @ 171 bar

  20. Manual Calculations • Laborious, Prone to Error • Disastrous Consequences • Desktop Software • V-Planner – VPM (www.v-planner.com) • Ross Hemingway, Eric Baker

  21. V-Planner Configure button Set surface interval Select the dive profile and mix Select your deco gases Use this button to enter a new deco gas Use this button to enter a new depth, bottom time and bottom mix

  22. Configure Parameters

  23. Enter Dive Details Calculate the dive profile

  24. Deco Profile & Gas Needs You must add 50% to these gas amounts to allow for Rule-of-Thirds.

  25. Rule-of-Thirds Bottom Mix: EAN 24: 2,733 x 1.5 = 4,099.5 (4,100 litres) 2 x 10-litre cylinders @ 205 bar For 210 bar fill: Turn Pressure = 210 x 0.66 = 150 bar Deco Mix: EAN 39: 500 x 1.5 = 750 litres 5-litre cylinder @ 150 bar EAN 80: 500 x 1.5 = 750 litres 5-litre cylinder @ 150 bar

  26. Summary • Individual gas consumption – RMV • Bottom mix • Deco mixes • Rule-of-thirds • Use of software

  27. Questions?

More Related