© 2005 The Professional Scuba Association International PSAI The Professional Scuba Association International Extended Range Nitrox Program

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© 2005 The Professional Scuba Association International

PSAIThe Professional Scuba Association International

Extended Range Nitrox Program

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PSAIProfessional Scuba Association International

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3© 2005 The Professional Scuba Association International

Extended Range Nitrox Overview

• Purpose of Extended Range Nitrox

• ERD Equipment• Oxygen Compatibility• O2 Exposure Limits

• CNS Oxtox• Pulmonary Oxtox• Tracking Uptake

• Computer Generated Dive Profiles

• Carbon Dioxide Excess

• DCI and DCS• Diving Procedures• Gas Management• The Math

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Performance Criteria

• Extended Range Nitrox academics is the course where we review your understanding of essential information.

• 80% passing grade required on written examination.

• Four open water training dives.• Must become comfortable and efficient

with all required diving skills.

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Skill Development

• Removal & replacement of stage cylinders with eyes open & closed

• Gas sharing• Gas shutdowns• Controlled deployment of a lift bag attached

to a dive reel

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Dive Planning

• The best PPO2 for bottom & deco Phases

• The best mix• Gas analysis• Gas needs for all phases of dive• MOD of bottom & deco gas• CNS clock at end of dive• The EAD• Deco planning

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The Purpose of Extended Range Nitrox• Focus on decompression diving• Selected optimum EANx mixtures for target

depth and time• Control of PPO2

• Controlling decompression efficiency and durationa) Allowing safer long duration divesb) Reducing the affect of inert gas narcosisc) Reducing the risks of DCS

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Controlling Deco Efficiency

• Example: 55 m dive for 20 min

Air only

12 m 4 min deco

9 m 6

6 m 9

3 m 22

Total Deco = 41 minutes

Air, EAN32, Oxygen

12 m 2 .32

9 m 5 .32

6 m 5 1.00

3 m 9 1.00


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Controlling Deco Efficiency

• Example: 180’ dive for 20 min

Air only

40’ 4 min deco

30’ 6

20’ 9

10’ 22


Air, EAN32, Oxygen

40’ 2 .32

30’ 5 .32

20’ 5 1.00

10’ 9 1.00


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Concerns of Extended Range Nitrox Diving• Requires more exact dive planning, less room for

error• Improper gas analysis, if done at all (or markings)• Increased equipment dependency, must become

efficient and comfortable with all equipment– What if a stage cylinder is lost or gas leaked out ?– What if the gas needs were miscalculated ?– What if the reel jams ?– What if a gas was mis-analyzed ?

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Concerns of Extended Range Nitrox Diving• Exceeding mix or ability limits.

– Why ERDs are more physically demanding ?• Nitrogen Narcosis, how do you cope with it ?• Oxygen toxicity (Oxtox)

– What is ConVENTID ?• DCI and DCS, we’re diving deeper with a

decompression ceiling• Exposures to High Altitude After Diving

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An Error in Philosophy

• When it comes to required equipment, most divers are recreationally minded

• Believing you can go to the surface at any time or relying on your buddy is an accident waiting to happen - Don’t fall into this trap

• Plan on being Solo competent

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A Sad But Honest Truth

When it comes down to live or die, if I run out of air … it is my problem & I hope you can help

BUT

If you run out and I don’t have enough to keep us both alive…

I will try to recover your body later

I expect you to feel the same

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Equipment

1. 3 or 4 member Team

2. Adequate gas supply

3. Twin Cylinders with 1.5m (5’) hose or better

4. 2 time & depth monitors

5. 2 slates

6. 2 cutting devices7. BCD with 27 kg (60#)

lift8. Dive lights9. Strong descent / ascent

line10.Safety cylinder,

regulator, octopus, & gauge at 7.5m – 9m (25’ - 30’)

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Equipment

11. Dive log

12. Adequate exposure suit

13. Surface float with slate attached

14. Lift bag (SMB) & reel

15. Spare mask

16.Two hour supply O2

17. Professional first aid kit

18. Save a dive kit

19. Equipment checklist

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Equipment

• Equipment considerations in general- Do not carry too much equipment- Be familiar with each team members equipment- Distribute equipment for proper balance for type of dive- Keep all equipment configurations clean and streamlined- Be able to access all equipment by touch contact

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Special Equipment Considerations

• SMB– Red, self sealing, marked with OK and initials– Yellow marked with HELP and initials

• Reel– Minimum length 1.5 x depth of first gas switch– (Spool as backup for lost SMB scenario)

• Correct inflation of an SMB– Before first gas switch– Use air in the wing and corrugated hose to avoid excess

buoyancy

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SMB Usage

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Special Equipment Considerations

• Long hose– Method of storing extra second stages

• Store under bungee on side of cylinder• Wrap in bungee behind head• Have long hose on unit to be given to diver in need,

either stowed along cylinder or wrapped around donor’s neck.

• Most PSAI ERDIs suggest handing off the unit that you are breathing from and having the backup unit located under your neck hooked up to surgical tubing.

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Stage / Deco Cylinders

– Minimum of 5 liters (45 cu ft) The dive profile and gas requirements for each phase of the dive will dictate cylinder volume.

– Safety guidelines for staging cylinders• Contents stickers and wraps to identify mix• Best to use high volume/double bladder BCD to support extra

weight

– All valves and regulators should match in case of failure

– Check gas before entering the water, and then turn valves off until needed for use

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Stage / Deco Cylinders

– Highest oxygen percentage cylinder worn on right side– Cover oxygen regulator mouthpiece to avoid improper

use– Have all clips set up for easy removal and replacement– Position stage cylinders to allow easy access to valves

and regulators and for proper trim for the type dive i.e., vertical or horizontal

– Equipment used with oxygen above 40%• Oxygen Compatible• Oxygen Clean• Oxygen Serviceable

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Nitrox & Equipment

• 40% or higher requires special cleaning

• Tank must be clearly marked for oxygen compatibility

• Label including mix, MOD, date analyzed

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Theoretical Concepts of Deep Diving

Oxygen toxicity = MODdefined by PPO2

Nitrogen narcosis, EAD

Decompression ceiling =STOP DEPTH AND TIME

Ascent speedand deep stops

Dee

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Sha

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er

On

gass

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zone

Off

gass

ing

zone

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Oxtox• The effect on the central nervous system ( the Paul Bert effect),

results in: – muscle twitching and spasm – nausea and vomiting – dizziness – vision (tunnel vision) and hearing difficulties (tinnitus) – twitching of facial muscles – irritability, confusion and a sense of impending doom – trouble breathing, anxiety – unusual fatigue – loss of coordination – convulsion.

Convulsion at depth in water usually results in drowning or arterial gas embolism. The occurrence of Oxtox may be reduced pre-planning your oxygen exposure while at depth.

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Oxtox• Pulmonary oxygen toxicity ( Lorraine Smith effect)

– Is a direct time /dose relationship on the lungs caused by a direct effect of O2 on the lungs, blockage of airways, increased CO2, pulmonary surfactant changes , enzyme interference and an inert gas effect. The best treatment is prevention and removal of pure O2 at the first signs of toxicity

– Usually characterized by temporary lung damage including chest pain, coughing, fluid in the lungs, the inability to take a deep breath and a reduction in vital capacity and can eventually lead to death

• “Whole body" toxicity which in addition to lung problems includes paresthesia (especially numbness in fingertips and toes), headache, dizziness, nausea, effects on the eyes and a reduction in aerobic capacity

• For practical purposes these effects are fully reversible once PO2s are reduced and leave no long term damage

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Oxtox

0.10 - Not enough – death is eventual result0.12 - Borderline function – asleep – body function shift

Hypoxic0.16 - Minimum necessary to sustain work – resting function

OK0.21 - Norm-oxic – we exhale 15% to 17% oxygen and 4% to

6% CO2 in normal conditions.0.30 - Normal saturation dive doses. Exposures are usually

24 hours or more.0.35 to 0.50 - Chambers and bells – low dose/long term,

less than 24 hours0.50 - Maximum saturation dive dosages – Lorraine/Smith

effect symptoms begins to manifest.0.60 - Pulmonary whole/body stress loads may be clocked by

utilizing Oxygen Tolerance Unit (OTU) values.

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Oxtox1.40 - Maximum dosage for extreme workload dives.

Paul Bert effect becomes more likely above this value.1.45 - Begins the caution zone for normal exposures and the limit

for high workload dives with regard to CNS toxicity – Paul Bert effect.

1.60 - Maximum dosage for normal dives or “open-water”decompression. Only 45 minutes single dive exposureas the limit.

1.60+ - CNS toxicity becomes a very likely occurrence – Paul Bert effect. Dosages in this range are very dependentupon time and CO2 loading.

2.0 - 100% oxygen a two ATA (optimize out gassing of nitrogen). For “at rest” only situations – Hyperbaric therapy.

2.4 - 2.8 Oxygen therapy at 6 ATA (to reduce bubble size and prevent bubble formation)

3.0 - 50% oxygen therapy at 6 ATA (reduce bubble size – maximum oxygen dosage). Short duration dosages –chamber therapy only.

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Central Nervous System Oxygen Toxicity

• What is the cause ?• How do you prevent it ?• What are the signs and symptoms ?• How do you reduce the risk ?

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• CNS Oxtox can lead to seizures and drowning• If you increase the oxygen in your breathing mix

imagine the bottom of the ocean getting shallower (PPO2 & NOAA table)

• Know what your MOD is• When in doubt, analyze• Use a PPO2 of 1.6 maximum for bottom gas under

ideal conditions

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Factors Which May Predispose Divers to Oxtox – Overexertion– Thermal Stress– Individual Susceptibility– Drugs

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Signs & Symptoms of Oxtox– Convulsion– Nausea (#1)– Muscular Twitching (#2)– Audio Disturbances– Visual Disturbances– Dizziness (#3)– Anxiety & Confusion– Irritability

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The NOAA Exposure Limits

Always be mindful of your exposure

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Tracking the CNS Clock

• The oxygen clock should be tracked during all phases of the dive:– Descent phase– Bottom phase– Time to first stop phase (first gas switch)– Decompression phase

Use the NOAA Oxygen Partial Pressure & Exposure Time Limits

• PPO2 maximum for descent and bottom phases– 1.6 for bottom phase under ideal conditions: warm

temperatures, low exertion, short decompression times

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• Remember to use: “air” break every 20 to 25 minutes. If air is not available, use the lowest PPO2 mix. PSAI recommends having air available at the first stop for emergency use.

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Computer Generated Dive Profiles

Decoplan.lnkV-Planner.lnk

Voyager Decoplan V-PlannerVoyager.lnk

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Carbon Dioxide (CO2) Excess

Catalyst for inert gas narcosis and Oxtox– Cause can be any of the following

• Poor physical condition of the diver• Bad diving habits

– Rushing to get ready for the dive– Swimming too fast, Stop, Get Control, Think, React– Exceeding personal diving and/or physical limits– Skip breathing, trying to conserve gas– Improper breathing rate under stress– Ego threat. Know when to say “No”

• Improper equipment• Low performance regulator

– Hard on inhalation/exhalation– Inadequate volume delivery at depth

• Inadequate fins or BCD• Too tight west suit, drysuit, weight belt or BCD

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Carbon Dioxide Levels and Effects• 4-6% Anxiety• 6-10% Impaired Mental

Capabilities• 10-15% Severe Mental Impairment• 15-20% Loss of Consciousness• 20+% Twitching & Convulsions

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• Headache• Euphoria• Weakness• Air starvation• Dizziness

• Confusion• Nausea• Tingling• Slowing of responses

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Decompression Illness and Decompression Sickness (DCI and DCS)

• What is the cause ?• How do you prevent DCI and DCS ?• What are the signs and symptoms ?• How do you reduce the risk ?

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REDUCING YOUR RISK• PLAN YOUR DIVE ~ DIVE YOUR PLAN• Use proper decompression techniques

– Keep chest at deco stop level– Don’t keep knees & elbows in bent position

• Dive with oxygen enriched air – EANx• Don’t exert. It is okay to swim during your

deco stop to keep warm. Don’t swim fast – just keep moving.

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REDUCING YOUR RISK• Keep properly hydrated• Stay in good physical condition• Make controlled buoyant ascents at a proper rate• After diving DO NOT:

• Exert• Take hot showers• Drink alcohol or caffeinated drinks for several hours• Fly or drive at high altitudes

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OXYGEN and DCI/DCS• Use during decompression reduces the risk

of DCI and DCS• Use for emergency first aid after a diver

surfaces with signs or symptoms of DCI or DCS may reduce the risk of permanent physical damage.

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Decompression Illness and Decompression Sickness (DCI and DCS)Omitted/Interrupted Decompression Emergency Plan On Air• US Navy when air diving (not for mixed gas dives).• Doubling the stops is recommended Extended Range

Nitrox procedure• Computer generated profiles simulating gas loss gave

mixed results, such as, for most profiles the procedure of doubling the required decompression stops worked well. It reduced the required decompress times. However on another it increased it. Again, this is why we keep repeating: Plan Your Dive ~ Dive Your Plan”

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Interrupted or Omitted Decompression• Repeat any stops deeper than 12m (40’)• At 12m (40’) spend 1½ of the time required at 3m (10’)• At 9m (30’) spend 1½ of the time required at 3m (10’)• At 6m (20’) spend 1½ of the time required at 3m (10’)• At 3m (10’) spend 1½ of the time required at 3m (10’)

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Neuro ExamPerform the following steps and place a check mark next to any area that has abnormal

or questionable results.1. ORIENTATION - Ask the diver's name, current date, and details about the dive.

Although the diver may appear alert, asking these questions may reveal confusion.2. EYES - Have the diver hold their head still and ask them to follow your hand (18

inches from diver's face) while you move it up-down and side to side. Their eyes should track smoothly in all directions and should not jerk from side to side. Check peripheral vision. See if pupils are equal in size and respond to light.

3. FOREHEAD - Have diver close eyes while you lightly touch diver's forehead and face. Check that feeling is present and note if there is a difference. With eyes shut tight, check for muscle strength by trying to open eyes above brow. Have the diver furrow brow. Note if there is a difference. Check for skin sensation.

4. FACE - Tell diver to whistle. Check to see if diver can pucker lips. Have diver smile. Note if there is a difference in facial muscles. Muscles should be of equal strength. Ask the diver to clench their teeth. Feel their jaw and note if there is a difference. Check for skin sensation.

5. EARS - Have diver close eyes. Ask if hearing is abnormal. Check hearing by holding your hand approximately two feet from the diver's ears and rubbing thumb and finger together. Move hands closer until diver hears sound.

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Neuro Exam

6. GAG REFLEX - Instruct diver to swallow while watching "Adams apple" move up and down.

7. TONGUE - Instruct the diver to stick out their tongue. It should come out straight, in the middle of their mouth, without deviating to either side.

8. SHOULDERS - Place hands firmly on diver's shoulders. Tell diver to shrug shoulders. Note if there is a difference in strength. Check for skin sensation.

9. ARMS - Have diver squeeze your fingers. Note if there is a difference in strength. Have diver grasp hands at chest level, elbows high. Gently push then pull elbows while diver resists motion. Note if there is a difference in strength. Check for skin sensation.

10. CHEST - Have diver close eyes. Check for skin sensation.11. LEGS - Have diver lie flat. Raise and lower legs while diver resists

motion. Note if there is a difference in strength. Have diver stand. Check balance and coordination by having diver walk heel to toe. Ensure that the diver does not fall. Check for skin sensation.

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Neuro Exam

IMPORTANT NOTE: The diver's condition may prevent the performance of one or more of these tests. Record the omitted tests and reason. The neurological exam should be repeated every hour. Record the results and report to medical personnel. Practice the neurological examination frequently to become proficient. One means of reducing the risk of decompression sickness is to dive with EANx. The advantage of diving Extended Range Nitrox mixtures is that we use optimum fractions of oxygen to control partial pressures as well as the duration and efficiency of our decompression.

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Dive Planning

Decompression gas choices– 40/80 or 50/100 ?– Benefits of using 80% oxygen for decompression

• Less vasoconstriction• Reduced CNS with minimum increase in decompression• May be breathed at 10m, enhancing off gassing. • Requires time for mixing, which may cost more due to the

time and equipment to blend.

– 100% • Easier to make• More frequent air breaks required

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Dive Planning

– Must determine depth, time and decompression before you can plan on gas requirements or ascent pressure.

– 2.24 Bar per meter (10 psi/foot) Guideline ?– Half plus 15 Bar (200 psi) Guideline ?– One Third Guideline ?– SCR in Bar (psi) ?– Converting Bar to liters (psi to cubic feet)?– Bar or liters (psi or cubic feet) at end of bottom time ?– Volume required for descent phase, bottom phase,

TTFS phase and the decompression phase ?

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Dive Planning

Your ERDI will now cover a gas matching example using the Thirds Rule

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Decompression Planning

SURFACE CONSUMPTION RATE (SCR)

Metric: (Bar / Time) X (10)

Depth + 10

Imperial: (Psi / Time) X (33)

Depth + 33

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Dive Planning

• Contingency Plan on the PSAI Slate– Exceeding target depth/time– Loss of decompression gas. Carry enough gas

and decompression tables to do all the decompression on the bottom mix if the decompression gasses are lost.

– Air stops– Use of tables in addition to dive computers

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Dive Planning

Gas Analysis• Formulas

– How do you select best mix ?– What is MOD and how do you use it ?– What is EAD and how do you use it ?– How do you use EAD formula to determine the

narcotic depth ?

• How do you analyze and mark your gas ?

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Decompression Planning

"T" Formula• Pg = partial pressure of a gas in a mix, either

resultant or desired (solve for EXPOSURE):Pg = Fg x P

• Fg = fraction of a gas in a mixture (solve for BEST MIX):

Fg = Pg / P• P = total pressure or Depth expressed in ATA

(Solve for Maximum operating Depth MOD):P = Pg / Fg

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Shallow Water Skills

Max depth 30’ (9 m)1. Remove and replace stage cylinder(s) with eyes open.2. Remove and replace stage cylinder(s) with eyes closed.3. With eyes closed, be able to identify each cylinder with touch

contact.4. Act as an out of air diver, with your mask flooded, and swim 30’ (9

m) to your buddy, while exhaling. Signal that you are out of gas, then while sharing gas, swim horizontally for 100' (30 m).

5. Close the valve to the primary regulator and switch to the backup, reverse the procedure and switch back to your primary gas source.

6. Attach the Iift bag to a reel, add gas to the bag, send it up to the surface while maintaining neutral buoyancy and not losing control of the reel.

7. Make a controlled buoyant ascent (CBA), stopping where required for decompression.

8. Practice skills 1, 2, and 5 while hovering with neutral buoyancy.

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Deep Water Skills

• DIVE 1: At a depth no deeper than 30 m (100’), remove and replace the stage cylinders, the cylinders must be replaced on the proper sides, make a controlled buoyant ascent. PSAI requires you to have the "hottest" mix on your right side. The depth, not to exceed 30 m (100’), will be determined by the instructor.

• DIVE 2: At any depth selected by the ERDI, no deeper than 30 m (100'), repeat the gas shutdown, and removing and replacing the stage cylinders. Then make a controlled, non-kicking, buoyant ascent.

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Deep Water Skills

• DIVE 3: From a target depth, no deeper than 30 m (100’), ascend to your first decompression stop while breathing on your instructor's alternate air source. Make a controlled buoyant ascent, while maintaining physical contact with the ERDI. A proper ascent rate of about 9 m (30’) per minute is critical.

• DIVE 4: After any required decompression, drop down to 18 m (60) and do the lift bag deployment in less than three minutes. Make a controlled buoyant ascent, while reeling the line up to the planned depth for decompression, or a safety stop. This skill should be practiced during all future dives.

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PSAI Technical Diving Programs• Cave • Nitrox • Trimix • Cavern • Dry Suit • Rebreather • Gas Blender• Full Face Mask• Twin Set Diving• Advanced Nitrox • Advanced Wreck• Narcosis Management • Technical Dive Rescue• Advanced Gas Blender• Extended Range Nitrox • Oxygen Service Technician• Visual Inspection Technician• Diver Propulsion Vehicle (DPV)

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Welcome to the real world of diving as a PSAI Extended Range Nitrox Diver!

Documents

© 2005 The Professional Scuba Association International PSAI The Professional Scuba Association International Extended Range Nitrox Program