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Chapter 6: KISS CCR Dive Planning

Chapter 6: KISS CCR Dive Planning. Gas consumption and planning Oxygen Diluent Bail Out Dive Planning Safety Stops O2 Tracking CNS Pulmonary A Quick Look at Decompression Dive Safety. Chapter 6: KISS CCR 1) Oxygen Gas Supply. A general guide for oxygen metabolism.

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Chapter 6: KISS CCR Dive Planning

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  1. Chapter 6: KISS CCR Dive Planning • Gas consumption and planning • Oxygen • Diluent • Bail Out • Dive Planning • Safety Stops • O2 Tracking • CNS • Pulmonary • A Quick Look at Decompression • Dive Safety

  2. Chapter 6: KISS CCR 1) Oxygen Gas Supply • A general guide for oxygen metabolism For the KISS target flow rate for orifice between 0.6-1 L/min, must be lower than divers actual metabolic oxygen requirement

  3. Chapter 6: KISS CCR 1) Oxygen Gas Supply • 13 ft3 cylinder = 1.8L • (13 ft3 x 28.3 L/ft3) / 204 bar = 1.8 L • 3000psi -500psi (reserve) = 170 bar • (2500psi / 14.7 psi per bar = 170 bar) • So we have a 1.8L cylinder with 170 bar = 306L • (170 bar x 1.8L = 306L) • Diver metabolic rate of 1 L/min and 306 L = 306 • minutes of time • (306 L / 1L per min = 306 min) • 306 min = 5.1 hrs of dive time off oxygen cylinder • Assume additional gas wastage for flushing the loop for deco, and hard work • Either way the O2 13 ft3 (1.8 L) cylinder should outlast the scrubber

  4. Chapter 6: KISS CCR 1) Oxygen Gas Supply • A more elaborate plan: • On descent assume hard work (2.5 L/min) for a 5 min • descent = 12.5 L • Dive at light work (1 l/min) for 40 min = 40L • Deco/safety stop at rest (0.5 L/min) for 5 min = 2.5 L • Total the above 12.5 + 40 + 2.5 = 55 L used for above dive • Diver has 13 ft3 (1.8 L) cylinder form above = 306 L and • enough Oxygen for the dive • Oxygen is mainly used up in times of hard work and on ascent

  5. Chapter 6: KISS CCR 2) Diluent Gas Supply • The diluent 13 ft3 (1.8 L) cylinder will only be used on descent to make up the loop volume, and to maintain buoyancy • The amount used will depend on depth and dive profile • NEVER use pure gases in diluent cylinder (i.e. pure He) always need some O2 in diluent • For deeper dives always start with fresh sorb and have at least 1500psi (102 bar) • Remember: saw tooth profiles, leaky masks, nose breathing all waste gas

  6. Chapter 6: KISS CCR Gas Supply Monitoring • Gas supply is not like OC • Cylinders are relatively small and usage should be small • Frequent depth changes, mask clearing, nose breathing can • all greatly affect gas supply and therefore it is important to • monitor SPG’s every few minutes • Also monitor PO2 every few minutes • ALWAYS KNOW YOUR PO2

  7. Chapter 6: KISS CCR 3) OC Bailout Gas Supply • Once the dive plan is known, ensure you have enough OC bailout gas to do an ascent and all saftey spots required in OC mode in case of complete CCR failure • Decompression diving is beyond the scope of this entry level KISS CCR course, this is covered in the KISS CCR mixed gas course

  8. Chapter 6: KISS CCR *3) OC Bailout Gas Planning METRIC* • See appendix B for formulas / conversions • Assume 40 msw (5 ata) OC RMV = 25 L/min • RMV at 5 ata = 125 L/min • 1 min to gain composure and signal buddy = 125L • Ascent (9 msw/min) to 4.5 msw stop will take 4 min =500L • 3 min stop at 4.5 msw (1.45 ata RMV = 36L/min) =109L • Total = 734 L • A 1.8 L cylinder full at 204 bar has 1.8L x 204 bar = 367 L and would not be enough • It will take a full 4 L cylinder (850 L of usable gas) to complete this bailout • It is essential to properly plan for OC bailout!!!

  9. Chapter 6: KISS CCR 3) OC Bailout Gas Planning IMPERIAL • See appendix B for formulas / conversions • Assume 132’ (5 ata) OC RMV = 0.8 ft3/min • RMV at 5 ata = 4 ft3/min • 1 min to gain composure and signal buddy = 4 ft3 • Ascent (30’/min) to 15’ stop will take 4 min =16 ft3 • 3 min stop at 15’ (1.45 ata RMV = 1.2ft3/min) = 3.6ft3 • Total = 23.6 ft3 • A 13 ft3 full at 3000 psi would not be enough • It will take a 30 ft3 to complete this bailout • It is essential to properly plan for OC bailout!!! • At a minimum a 30 ft3 OC bailout should be on all no deco recreational CCR dives

  10. Chapter 6: KISS CCR Dive Planning • Dive planning: • Air computer / air tables • Nitrox dive computer • Constant PO2 tables (USN) • Constant PO2 dive computer • PC generated dive tables for constant PO2 • Only present method students will use

  11. Chapter 6: KISS CCR Air Computer / Air Tables • Make sure not to violate PO2 or the Oxygenclock • Use air computer or tables following the ND limits or decompression limits • Gives the diver a huge physiological inert gas advantage • Find depth at which set point (PO2 ) for the dive will equal21%O2, and do not go deeper than this depth on air tables, or you will take on more inert gas than the air tables calculate • See following slides

  12. Chapter 6: KISS CCR Ensure Set-Point and MOD Acceptable • If the PO2 set point was 1.0 atm • PG=FG x Data • 1.0 atm=0.21 x Data • 124 fsw (38msw) is the MOD at which point the CCR diver will be taking on more nitrogen, affecting narcosis and decompression Not recommended to Dive below 130 fsw (39 msw) on Nitrox, use heliox or trimix

  13. Chapter 6: KISS CCR Dive Planning: END • PN2 = 0.79 x 5 ata (132 fsw, 40 msw) • MND (narc) = PO2 + PN2 • MND = PO2 + 3.95 ata • The following table show various set-points and resulting depth will equal 132 fsw (40 msw) on air

  14. Chapter 6: KISS CCR Dive Planning: END

  15. **Chapter 6: KISS CCR** EAD and END • An Aside on the relationship between EAD and END • The above discussion talks about how to find the maximum depths to take the CCR for EAD and END. • To Figure out END we need to find out how much of the gas being breathed at various depths is nitrogen (this is assuming that we believe that oxygen is not as narcotic as nitrogen). • Ptotal – PO2 = PN2 • So the diver at 5 ata at a set point of 1.3 atm would have a pressure of 3.7 atm of N2 • Now we can compare this pressure of nitrogen to what it would be for air, this will give us the EAD. The favorite formula PG = FG x Data, assume set point 1.3 atm and diver is at 132 fsw (40 msw): • 3.7 atm = 0.79 x Data • 4.7 atm= Data • (4.7 atm – 1 atm) x 33=122 fsw • (4.7 atm – 1 atm) x 10 = 37 msw

  16. **Chapter 6: KISS CCR** EAD and END • From this the diver will actually be at 132 fsw (40 msw), but will feel like they are at 122 fsw (37 msw) when comparing the narcosis level. • Also the diver may use the 122 fsw (37 msw) air table to plan the dive. • If you are a diver who likes formulas then the two formulas for the above calculations would be: • Ptotal – PO2 = PN2 • (PN2/0.79 - 1) x 33 = EAD • METRIC: (PN2/0.79 – 1) x 10 = EAD • This EAD can now be used for dive planning using an air table • Also we can see if our mix is more or less narcotic than air at the depth we are diving at.

  17. **Chapter 6: KISS CCR** EAD and END: IMPERIAL This is the relationship between EAD and END. The following table will summarize EAD and END for various depths and set points.

  18. **Chapter 6: KISS CCR** EAD and END: METRIC This is the relationship between EAD and END. The following table will summarize EAD and END for various depths and set points.

  19. Chapter 6: KISS CCR Dive Planning: Nitrox computer • Take PO2set-point (be a bit conservative here, use 1.2 atm if the actually desired is 1.3 atm) • Figure out MOD and use formula (PG=FG x Data) to convert to comparable OC nitrox mix) • Ex) MOD = 132 fsw (40 msw) PO2 desired =1.3 atm thus use 1.2 atm • PG=FG x Data • 1.2 atm = FG x 5 ata • 1.2 atm/5 ata = FG • Program nitrox computer for 24% • Will not give CCR advantage of constant PO2 , but will increase safety factor, monitor O2 Clock at a PO2 of 1.3 atm!!!!

  20. Chapter 6: KISS CCR Constant PO2 Tables • See Appendix I for the USN constant PO2 0.7 atm tables • A CCR diver may use these tables to plan their dives • The recreational diver would be well advised to add some safety factor. This can be easily done by keeping a PO2 of 1.0 atm – 1.3 atm in the breathing loop when using the USN 0.7 atm tables. (watch the CNS oxygen clock) • The Buhlmann constant PO2 tables offer a PO2 range from 0.8 atm to 1.6 atm.

  21. Chapter 6: KISS CCR Dive Planning: PO2Computer • Constant PO2 dive computer: • Set conservative PO2 i.e. use 1.2 atm if attempting to run dive at 1.3 atm • Computer will calculate whole dive on constant PO2 • Will allow for increased time or less deco • Will not give physiological safety advantage • Watch out for PO2 changes, if PO2 falls, dive computer will not take this into account • Ensure you do not violate the Oxygen clock

  22. Chapter 6: KISS CCR Dive Planning: PO2 computer • Constant PO2 “on-line” dive computer: • This form of dive computer (VR3 or HSE) will actually have its own O2 sensor in the breathing loop • Before the dive the sensor must be calibrated and the diluent gas programmed • This allows for the computer to adjust dive profile in real time with the actual PO2 the diver is using • This is safer if the PO2 drops in the loop as the computer will take into account the extra inert gas that is loading

  23. Chapter 6: KISS CCR Dive Planning: PC Generated Tables • This method can be used for ND dives and is recommended for decompression diving • The diver plans the dive on PC before dive • Hand writes (or prints and laminates) dive specific tables, and OC bailout tables for the specific dive • This method is a bit more time consuming in the preparatory phase, but is highly recommended in case of UW computer failure

  24. Chapter 6: KISS CCR Safety / Decompression Stops • Once familiar with the buoyancy characteristics of the KISS CCR the safety / deco stop will be easier to maintain vs. OC, as breathing will not affect buoyancy • When you arrive at 20 fsw (6 msw) you may increase the PO2 to 1.4 atm • Make sure to control buoyancy, and have pre-planned for the extra oxygen clock consumption before the dive • If not at a static stop deploy SMB

  25. Chapter 6: KISS CCR CNS Clock

  26. Chapter 6: KISS CCR CNS Clock • Make sure not to violate the maximum CCR PO2 of 1.3-1.4 atm • Make sure not to violate the O2 clock • Tracking the clock is relatively easy as compared to OC • Take the dive time and multiply by the factor at your set point • Ex. 1.3 atm PO2 for 50 minutes • 50 minute dive • 50 minutes x 0.56 % CNS/min = 28% of clock for the dive • 5 minute safety stop at 1.4 atm • 5 min x 0.67 % CNS/min = 3.35% • Dive total = 28% + 3.35% = 31.35%

  27. Chapter 6: KISS CCR Pulmonary Exposure • If you follow the CNS clock the pulmonary oxygen exposure is usually not a problem. But tracking is still suggested • If you are doing multiply dives over many days (4 hrs of dive time per day) with a PO2 of 0.9 atm or less then the pulmonary toxicity may be a concern • If you are using a higher PO2 like 1.0 atm or above then the CNS clock will usually limit the time

  28. Chapter 6: KISS CCR A Quick Look at decompression • SCR = variable FO2, only at MOD is the PO2 the greatest but still less than OC nitrox dive • CCR = constant PO2 and therefore at any depth the PO2 is at it’s maximum • Consequently the amount of inert gas is always at its minimum for the depth • This allows for less inert gas uptake into the body • Allowing either longer ND dive times, or less Decompression, as compared to OC or SCR • This also allows for ease in calculating the O2 Clock (PO2 factor x dive time)

  29. Chapter 6: KISS CCR A Quick Look at decompression • Assume PO2 1.3 atm on a CCR dive compared to an OC air dive • The CCR diver will only start to take on inert gas at 36 fsw (11msw), and will also no longer be taking on inert gas on the ascent at 36 fsw (11 msw)

  30. Chapter 6: KISS CCR Dive Safety • ALWAYS KNOW YOUR PO2 • Monitor PO2 often every 1-4 minutes and more often closer to • the surface (no safety prompts) • If you suspect a sensor failure during the dive do a diluent • flush, and watch for PO2 change. • Ex) if at 132’ (40 msw) you do a diluent flush (assume air • is diluent) simple math will tell you (PG=FG x Data) 0.21 x 5 • ata= 1.05 atm • This procedure will use up considerable gas supplies, • ensure the gas supplies are adequate before attempting

  31. Chapter 6: KISS CCR Dive Safety • Another sensor verification method is to watch the third decimal point, it should be moving • Monitor SPG for both O2 and diluent (not as critical as in OC, but still good practice) • Always be aware of gas venting or addition, and what it means to your PO2 • On ascents it may be more comfortable to vent some of the loop gas thought your nose/mouth (especially if you experience “chipmunk” cheeks), watch PO2 • On descents go slow!! If a breath is not available due to rapid descent flip to OC for a rescue breath, and slow down!!

  32. Chapter 6: KISS CCR Dive Safety • DO NOT exceed 30’/min (9 m/min) ascent rate • Deep slow breaths are better than fast skip breaths: allows gas the greatest contact time with the sorb allowing mose efficient CO2 removal • Never hold your breath • Swim with a 45 degree head up position to minimize the hydrostatic effects on breathing • If you flip onto your front, you will automatically inflate your cheeks!! • Always start deep dives with a fresh sorb (150 fsw or 45 msw) • Always dive KISS CCR with a reliable buddy

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