1 © 2005 The Professional Scuba Association International PSAI Professional Scuba Association...

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1© 2005 The Professional Scuba Association International

PSAIProfessional Scuba Association International

Trimix Program

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PSAIProfessional Scuba Association International

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Trimix Overview

• Purpose of Trimix• Hypoxia• Hypothermia• Decompression

Considerations• Narcosis• Determining

Mixes

• Types of Trimix• Gas Management• CNS Tracking• Omitted/Interrupted Decompression

• Dive Planning• Instructor Dive Plan• Dive Skills

• Types of Trimix• Gas Management• CNS Tracking• Omitted/Interrupted Decompression

• Dive Planning• Instructor Dive Plan• Dive Skills

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Performance Criteria

• Trimix academics is the part of the course where we review your understanding of essential information.

• 80% passing grade is required on written examination.

• Four open water training dives – Level 1.• Two open water training dives – Levels 2 & 3.• Must become comfortable and efficient with all

required diving skills.

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Performance Skills

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

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

attached to a dive reel

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Equipment• Trimix equipment is considerably more complex

than deep air SCUBA.• Different gas mixtures must be clearly identified

- Color code cylinders, regulators, and gauges.• Remember - each gas may not be breathable at

all dive depths. For decompression mixtures: Highest O2 goes on diver’s right and lowest O2 on the left.

• Drysuit inflation must not be run from mixtures containing helium - too cold!

BASIC TRIMIX GAS SYSTEM

CONTENTS GAUGE

INFLATOR HOSE

DECO &NITROXTRAVELMIX

TRIMIX X 2

DECOMPRESSION GAS

Make your equipment appropriate to your dive plan.

REGULATOR

2m HOSE

ARGONSUITINFLATION

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Other Equipment

• Line reels• Decompression equipment• Thermal equipment• Tables• Mixed gas computer• Appropriate analyzer

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Line Reels

• Should contain enough line to be used as an ascent line from the maximum depth of the dive.

• Should have some kind of locking mechanism.

• Line use requires shallow water practice.

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Decompression Equipment

• The basic equipment every Trimix diver should carry is:• A surface marker buoy, maybe two.• Line reel, maybe two.• Jon-line under some situations, especially when boat

diving.

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Thermal Equipment

• Appropriate dry suits - membrane or crushed neoprene.

• Appropriate underwear - thinsulate and base liner.

• Consider Argon inflation systems for very cold water.

• Protect main areas of heat loss.• Keep the core warm from inside out.

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Redundancy

• Redundancy means taking enough equipment to allow for Murphy’s Law.

• Murphy states that something is bound to fail, usually at the most inconvenient time.

• If something can go wrong, it will – when you least expect it.

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Take Two

• Any item of gear, the failure of which may endanger your life, you should have a spare.

• This includes regulators, depth gauges, dive computers, buoyancy devices, lights, timer devices, decompression tables, masks, knives, reels, SMBs, etc.

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Solo Diving

• PSAI does NOT encourage or condone solo diving.

• PSAI has a strong stance against the teaching of any course that would be seen as suggesting to divers that solo diving would be okay.

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Important Philosophy

• You should be capable of getting yourself out of any situation you get into underwater.

• You should not have to depend on endangering another’s life to save your own.

• Every good diver is a self-sufficient diver. This allows diving as companions rather than as “dependant buddies”.

• NEVER DIVE SOLO!

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Ancillary Equipment

• Fins - appropriate to environment.• Masks - low profile, large area for warmth. Must

have redundant mask.• Knives - cutting ability rather than machismo.

Two cutting devices required. One may be wire cutters. Keep small.

• Lift bag/SMB plus small reel.• Wreck tools ( Hammer, Chisel, Crow bar,

Cutters). Sometimes it’s nice to look rather than take!

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Streamline

• Make sure regulator hoses are run correctly. • Clip contents, gauges and consoles where they

can be seen, but where they do not hang too low. • Do not allow them to entangle, kink, dangle or

protrude.• Make sure regulators are accessible for normal

use and in emergencies.• Streamlining protects equipment as well as

making it easily accessible.

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Computers and Gauges

• Back up with appropriate hard tables. Take two.

• Each stage regulator must have it’s own gauge.

• Two timers, two depth gauges.• Compass.

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Dry Suits

• Dry suits are made from foam neoprene, crushed neoprene, and various membranes.

• At depth, these keep the water out (mostly).

• Plan to stay comfortably warm throughout the dive.

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Layers of Warmth

• The most efficient way to stay warm is to wear several layers under a drysuit.

• Start with a wicking fabric to avoid damp spots next to the skin.

• Follow with a layer of lightweight polypropylene underwear, and top with a layer of Thinsulate.

• Thinsulate works with 80% of its dry thermal value when wet.

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Thermal Equipment Suggestions

• Use proper dry suits and keep them serviced - leaks may cause hypothermia on long dives requiring decompression.

• Use proper underwear - several layers can be better than a single layer under the suit. Make sure it continues to work when wet.

• Use argon suit inflation - it can provide 1.7 times more insulation than air.

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DON’T BLAME YOUR TOOLS!

• Understand your equipment.• Use it appropriately, within its design

specifications.• Know when not to use it.• Make sure all equipment is safe and

serviced.

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Trimix Defined

A mixture of helium, nitrogen and oxygen.

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Helium

Characteristics

• Low solubility and high diffusivity in tissues, moves easily (quickly) in and out of tissues.

• Non-narcotic and non-toxic at open-circuit depths.

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Helium

Tissue Solubility

• Helium enters tissues rapidly, up to 2.65 times faster than nitrogen, and leaves them rapidly.

• This requires a different decompression profile with decompression starting deeper than for air, with short stops at depth.

• Helium decompressions can be reduced by the use of nitrox at shallower depths.

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Helium

Physiological effects

• Vocal distortion.• Apparent chilling during breathing.• High pressure nervous syndrome

(HPNS).

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Advantages of Trimix

The percentage of oxygen in the breathing mixture can be set for a specific depth allowing: • The diver to set a maximum PPO2 at depth. • Control of the CNS exposure and oxygen clock.

Making deeper dives possible. Permitting longer bottom times on deeper dives.

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The percentage of nitrogen in the breathing mixture can be set allowing the diver to:– Manage the narcosis levels by selecting a

specific Equivalent Narcosis Depth (END) for the dive.

– Dive deeper with less risk from nitrogen narcosis.

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Compared with Heliox (oxygen and helium) breathing mixtures, Trimix allows a reduction of High Pressure Nervous Syndrome (HPNS) risk.– With as little as 12 – 25% of nitrogen in a

breathing mixture (depending on depth and compression rates) the buffering effect of the nitrogen can offset the effects of helium that may cause HPNS.

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• A physical manifestation of a high pressure gradient across tissue compartments, compounded by helium breathing.

• Exacerbated by rapid pressurization to depths of over 120 meters.

• Symptoms: muscle tremors, drowsiness, loss of appetite, nausea, dizziness, vertigo, visual disturbances, difficulty in concentrating.

• Reduced by slow and staged pressurization, and by adding small amounts of nitrogen to “relax” tissues.

HPNS – a bit more informationHPNS – a bit more information

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Trimix allows us to control (lessen) the density of our breathing mixture.

• Less density means a reduction in the work of breathing (WOB):– Carbon dioxide retention is lowered.– The Surface Consumption Rate (SCR) will tend to

be reduced.

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Concerns of Trimix

Expense:• Trimix is a more expensive breathing mixture

than air or nitrox due to the cost of helium.• Also more expensive because of the complexity

of:– Gas mixing. – Analysis. – Production.

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Concerns of Trimix

Trimix diving calls for increased dive planning and discipline.

• Critical elements are the planning and monitoring of depth, time, decompression and gas supplies.

• Gas switching underwater is required.• Helium is non-forgiving when it comes to run

times, gas switches, and ascents.

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Concerns of Trimix

Helium-based DCI can be more hazardous than nitrogen DCI.• Ascent rates are critical.• Buoyancy control is critical.• Decompression stops must be:

– Precise.– Controlled.– Stable.

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Concerns of Trimix

Complicated decompression requires:• Custom dive tables which must take into

account such variables as:– Travel gas.– Decompression gases.– Which trimix mixture will be used.– Alternative depth and times.

• Several Trimix dive computers are on the market. Custom tables are carried as backups in case of computer failure.

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Hypoxia

• In order to reduce the physiological problems associated with Oxtox in deep diving we lower the percentage of oxygen in the bottom mix, which in turn allows us to maintain the desired PPO2 at maximum depth. However, by doing so, we increase the chances of being exposed to hypoxia with certain bottom mixes.

• Hypoxia may result when breathing mixes below 16% oxygen.

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Hypoxia

• May be prevented by the use of travel mixes.

• Advantages of travel mixes:– Reduced helium uptake.– Reduced decompression.– Decompression efficiency.– Reduced chilling caused when helium is in mix.– Selection of best travel mixes.

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Hypoxia - Symptoms

• A feeling of well-being• Tingling• Numbness• Visual disturbances• Confusion • Impaired judgment

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Hypoxia - Symptoms

• Paresthesia (Burning, itching, prickling)• Formication (Feels like ants crawling on

the skin)• Cyanosis• Loss of coordination• Loss of consciousness• Death

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Hypoxia - Prevention

Prevention of Hypoxia:• Know what you are breathing. Always analyze

your gas before diving.– Use proper grade of compressed air in mixes.– Analyze Nitrox mixtures.– Analyze Trimix mixtures.

• Don’t skip breathe.• Don’t smoke prior to diving.• Get proper training for breath-hold diving.

– Don’t hyperventilate prior to a breath-hold dive.• Avoid prolonged or very deep breath-hold dives.

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• Keep equipment well maintained.– Cylinder visual inspection– Regulator annual servicing– Annual gauge check for accuracy– BCD annual servicing

• Follow safe diving rules. “Plan Your Dive ~ Dive Your Plan.”

• Pre-plan and monitor your gas supply, use the PSAI Gas Management Sheet.

• Know proper out-of-air procedures. However, running low or out of gas is not an option.

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• Continue your dive education. • Use the PSAI Gas Management Sheet.• Maintain and/or improve dive skill levels.

PRACTICE, PRACTICE, PRACTICE!!!!• Determine the minimum depth a hypoxic mix

may be used and don’t use it any shallower.• Any mix containing less than 21% O2 may be

hypoxic under certain conditions.• When needed use a travel mix (descent mix).

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Hypothermia

Mixes with a high percentage of helium, usually greater than 20%, increase the risk of hypothermia.

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Hypothermia - Symptoms

• Fatigue• Numbness• Excessive need to urinate• Loss of ability to think clearly• Shivering which may lead to the loss of

physical control and cause the diver to lose the regulator mouthpiece.

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Hypothermia - Symptoms

Body Core SymptomsTemperature• 98.6 This is the normal body temperature.• 97.0 This is the core temperature noted for

divers after a six hour exposure in a high quality dry suit in near freezing water.

• 95.0 This is the lowest limit of a “safe” decline noted in divers who are well conditioned.

• 94.0 At this temperature there is memory loss and lack of coordination.

• 90.0 Heart rhythm become irregular.• 86.0 Unconsciousness may occur, noted loss of

musclestrength.• Less than 86 Death usually occurs with severe depression of

cardiac and respiratory activity.

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Hypothermia - Prevention

Thermal protection:• Proper fitting 7 mm wetsuit combination.• Use of a cold water diving hood.• Dry suit with proper undergarments and

maybe an argon dry suit inflation system.

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Hypothermia - Prevention

Proper drysuit inflation gas.• Do not use helium mixes for suit inflation:

– Costly.– Increased risk of hypothermia.– Potential skin DCS.

• Consider the use of argon as a dry suit inflation gas:– Better thermal properties than air or nitrox mixes.– Do NOT breathe argon! This can result in anoxia

and the diver becoming unconscious.

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Hypothermia -Argon Suit Inflation

• Flush the suit with argon to remove air before diving, or before decompression.

• Identify argon cylinder, mark clearly: ARGON – DO NOT BREATHE.

• Use a cylinder valve and reducer which are incompatible with breathing gas cylinders to avoid the potential for asphyxiation.

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Decompression Considerations

Helium produces rapid on-gassing!

Compared to nitrogen, helium is absorbed by the tissues of the body 2.65 times faster.

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• During the ascent phase of the dive, the diver must employ gas-switching to get off the helium mixture ASAP. This results in:– Reduced decompression.– Reduced risks of DCS.– Reduced chilling.

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• Ascent rates for Trimix diving are critical!– Too fast: The risk of developing DCS is much

greater than air or nitrox mixtures.– Too slow: The on-gassing of helium is not

accounted for and this may result in DCS.– The recommended ascent rate is 9 meters per minute

(30 feet per minute).– Some dive table software will allow the diver to

specify even slower ascent rates.

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• Stability at depth (buoyancy control) is critical.– Switching gases – Decompression stops

• Wave action may affect stability.– Use of an SMB and line– Use of a Jon line

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Decompression must be tracked accurately!• Use of accurate digital gauges.• Use of dive timer, watch, or stopwatch.• Use of Trimix dive computers.• Use of custom computer generated tables.• Decompression “stop time” vs. “run time”.

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• 80% oxygen vs. 100% oxygen for deco.• Benefits of 80%:

– Reduces the CNS clock %.– Little or no increase in deco time compared with

100%.– Can be used at 9 meters (30') – possibly better out-

gassing.

• Disadvantage:– More difficult to mix due to higher pressure

requirements.

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• Five minute air breaks should be taken every 20-25 minutes when:– You are using 100% oxygen.– Your deco gas PPO2 is 1.6.

– Your CNS clock is 80% or greater.

• The 5 minutes of each air break is not to be counted in the decompression time (air break time is additional deco time).

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• Decompression tables must include: – Primary table.– Redundant table.– Contingency table.

• Next greater time.• Next greater depth.

– Bail out table.– Gas loss table in the event of loss of EANx or O2 for

decompression.

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Extra cylinders staged at critical locations provide extra decompression gas (EANx or oxygen) in case of a gas supply failure or an emergency where extra deco gas is required.

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• Team members should match:– Travel gases.– Bottom gases.– Decompression gases.– Regulator first stage types: (DIN or “Yoke”).

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Narcosis

The “T” Formula

Pg

Fg P

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Narcosis

END Formula

metric

(END desired + 10 X .79 / depth + 10) = N2%

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Narcosis

END Formula

imperial

(END desired + 33 X .79 / depth + 33) = N2%

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Narcosis

EAD Formula

Metric

EAD = [FN2 / .79] x [depth + 10] - 10

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Narcosis

EAD Formula

Imperial

EAD = [FN2 / .79] x [depth + 33] - 33

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Finding the Percentage of O2

• Desired PPO2 and depth in ATA = O2 % (Best Mix).

• Pg = Partial pressure of a gas in a mix, either resultant or desired (solve for EXPOSURE).

• Fg = fraction of a gas in a mix (solve for BEST MIX).

• P = total pressure or Depth expressed in ATA (solve for MOD).

• Pg = Fg x P Fg = Pg/P P = Pg/Fg

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Determining Mixes

Metric

Let’s say you desire a 40 MSW narcosis level at

91 MSW with a maximum PPO2 of 1.4.

What would be the percentages of the three gases.

Formulas Answers1. PO2 = 1.4 [13.87% O2]

2. FN2= (40 + 10) x .79/[91 + 10] = 39.1 [39.1% N2]

3. FHe = 100 - 13.87 - 39.1 = 47.03 [47.03% He]

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Determining Mixes

Imperial

Let’s say you desire a 131 FSW narcosis level at

299 FSW with a maximum PPO2 of 1.4.

What would be the percentages of the three gases.

Formulas Answers1. PO2 = 1.4 [13.87% O2]

2. FN2= (131 + 33) x .79/(299 + 33) = 39.1 [39.1% N2]

3. FHe = 100 - 13.87 - 39.1 = 47.03 [47.03% He]

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Determining Mixes

Determining unknown He content in a HeliAir mix.

A mix is analyzed and the analyzer shows the percentage of O2 to be 13% at 232 bar (3000 PSI). The following steps can be used to determine the helium (He) content:

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Determining Mixes

HeliAir MixturesMetric

• Multiply the O2% by the total pressure: .13 X 232 = 30.16 bar of O2.

• O2 bar divided by the fraction of O2 in air, which is .21. 30.16/.21 would equal 143.6 bar.

• Subtract the above answer from the total bar, 232 – 143.6 = 88.4. This means that the mixture would have 88.4 Bar of He.

• Divide the above answer by the total Bar to find the fraction of He. 88.4 divided by 232 equals .38, which means that the helium concentration represents 38%. This shows the mix to be a 13/38 Trimix, 13% O2 38% He and 49% N2. This formula is only for HeliAir mixtures.

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Determining MixesHeliAir Mixtures

Imperial• Multiply the O2% by the total pressure: P .13 X 3000 = 390 PSI

of O2.• O2 PSI divided by the fraction of O2 in air, which is .21.

390/.21 would equal 1857.• Subtract the above answer from the total PSI, 3000 - 1857 =

1143. This means that the mixture would have 1143 PSI of He (79 Bar). To convert PSI to Bar you multiply the PSI times .06895. One PSI equals .06895 Bars.

• Divide the above answer by the total PSI/Bar to find the fraction of He. 1143 divided by 3000 equals .381, which means that the helium concentration represents 38%. This shows the mix to be a 13/38 Trimix, 13% O2 38% He and 49% N2. This formula is only for HeliAir mixtures.

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Determining Mixes

• For “Stacked” or “Custom” mixes:–The ONLY way to accurately

determine the Helium content is to use a Helium analyzer!

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Types of Trimix

HeliAir

Starts with a cylinder filled with a desired pressure of helium and then is topped

with air.

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Types of Trimix

HeliAir – Advantages• Simple to make fill calculations.• You ALWAYS will know BOTH of your inert

percentages (nitrogen and helium) from measuring the oxygen percentage.

• You are never dealing with anything above “Normoxic” 21% in your Bottom Mix – giving a greater margin of safety.

• You can safely re-mix your bottom mix cylinders for another dive without the worry of not knowing the percentages of your inert gases (Helium and Oxygen).

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Types of Trimix

HeliAir – Advantages• Safe multiple remixing can lower the cost of the bottom

gas for Trimix Diving since you may only be topping with air.

• Lowered costs may increase the number of dives you engage in thus increasing experience.

• The vast majority of Trimix dives can be performed with HeliAir as an appropriate bottom mix.

• Remix calculations are simple.• Calculations to figure inert gas percentages after

analyzing the oxygen in the mixture are simple.

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Types of Trimix

Stacked Trimix

This mix requires both oxygen and helium to be added to the cylinder before

topping up with air.

To dive this type of mix safely, it must be analyzed with both a helium and an

oxygen analyzer!

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Gas Management

DATA

• Depth• Air • Time• Awareness

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Gas Management

• The awareness should be:– Self awareness.– Buddy awareness.– Equipment awareness:

• Your equipment.• Your buddies’ equipment.

– A total awareness of the dive profile, and environmental conditions, which can change at any time during a dive.

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Gas Management

Too often divers fail to properly monitor all team member’s gases and allow a low gas situation to develop.

This is unacceptable, just don’t let it happen!

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Gas Management

Four Phases of a Dive Requiring Gas Management Planning

• Descent phase• Bottom phase• Time to first stop phase• Decompression phase

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Gas Management

Thirds RuleUsed for penetration dives in physical overhead environments:

– Wreck– Cave– Cavern– Ice

Used for excursions away from planned ascent line.

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Gas Management

PSAI suggests that no matter which gas management guidelines you are using to

plan your dive:

You should reach the surface with 35 bar (500 psi) remaining in any cylinder.

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Gas Management

Definitions:• Surface Consumption Rate (SCR)• Surface Air Consumption (SAC)• Respiratory Minute Volume (RMV)

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Gas Management

Gas Consumption Rates• SCR (SAC) always expressed in terms of

pressure used per minute: bar per minute (psi per minute).

• RMV always expressed in terms of volume used per minute: free liters per minute (cubic feet per minute).

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Gas Management

• SCR (SAC), pressure consumed per minute, changes with different sizes of cylinders.

• RMV, volume consumed per minute, does not change with different size cylinders.

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Gas Management

Calculating SCR (SAC)

SCR = {Pressure Consumed ÷ Bottom Time} ÷ Average depth in ATA

To calculate depth in ATA:Metric

ATA = {Depth ÷ 10} + 1Imperial

ATA = {Depth ÷ 33} + 1

Note: If the diver was using twin (double) cylinders, the SCR must be multiplied by TWO.

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Gas Management

Converting SCR (SAC) to RMV

RMV = SCR × {Rated Volume ÷ Rated Pressure}

Note: The rated volume and rated pressure must be the rated volume and pressure of the cylinder the SCR (SAC) was calculated on.

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Gas Management

Converting pressure to volume:

Volume = {Rated Volume ÷ Rated Pressure} × Actual pressure

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Gas Management

Your EDRI will now work gas management examples with you.

You will also plan a dive using the PSAI Gas Management Worksheet.

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Gas Matching

• Used for penetration dives.• Used with dissimilar sized tanks.• Used with dissimilar surface consumption

rates.

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Gas Matching

• Buddies should be gas matched as close as possible.

• Buddies should have same RMV and same tank sizes OR diver with lowest RMV carries gas sufficient for other divers’ RMV.

• Lowest RMV has highest volume cylinder (highest RMV has lowest volume cylinder).

• AND the plan must be done based on the smallest tank size available in the team.

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Tracking CNS Exposure

• Oxygen tracking must keep the diver within CNS percentage limits at all points of the dive.

• Tracking must include travel and decompression times, and must allow for gas switching.

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• CNS tracks the potential for CNS toxicity. This is tracked in the form of a “CNS Clock” giving us a percentage of the clock used (with 100% being the maximum allowed exposure).

This procedure was co-developed by PSAI President Gary Taylor along with Tom Mount and Mark Owens. It is now used universally by all technical training agencies to track CNS exposure.

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CNS % = Time at PO2 / Time Limit at PO2

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Tracking DecompressionThe diver should carry the following schedules:• Primary decompression schedule, for a dive according to the dive

planned, carry two sets.• Bailout decompression schedule in case of an early abort.• Contingency decompression schedule in case depth and/or bottom

time is exceeded.• Ascent travel mix not available due to loss or malfunction of

equipment.• Oxygen planned for decompression not available, as in the previous

bulleted item above.• Neither oxygen nor Nitrox available for planned decompression

gases, requiring that all the decompression be completed with the bottom gas. Very few divers would have enough gas for this contingency.

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Tracking Decompression

Underwater Contingency Plans:• Switching to the wrong gas:

– Immediately switch to back gas, locate and switch to the proper gas. Each diver must positively identify the mix and depth when a gas switch is made.

• Missed Gas Switch: – Use contingency schedule.

• Wrong or Skipped Decompression Stop: – Add the amount of missed time to the next stop

and go to the schedule for the next greater depth and bottom time.

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Omitted or Interrupted Decompression• If both decompression gases are lost and the bottom mix is used

for decompression, doubling the stops may prove to be beneficial on the deeper stops but not on the shallower ones.– Some of the computer generated profiles that were run required up to 13

times the decompression time at the 3m (10') stop when conducted with various bottom mixes.

• If the EANx decompression gas is lost and the bottom mix is used in its place, to decompress with, the above procedure may work. However, when using O2 at the 6m and 3m (20' and 10'), it may be wise to triple the time at each stop, providing the CNS clock is not violated.

• On some of the computer generated profiles calling for using EANx during the entire decompression, because of a loss of O2 at the shallow stops, doubling the stop times may work successfully without exceeding the CNS clock, however on others the CNS% was exceeded.

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© 2005 The Professional Scuba Association International

Dive & Decompression Planning

“The trouble with most divers is they ain’t seen the varmint!”

Sheck Exley.

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Dive Planning

1. Dive objective:• Train other divers• Underwater survey• Search and recovery• Check diver’s inert gas narcosis• Explore new areas• Just to have a great fun dive

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Dive Planning

2. Depth

3. Bottom time

4. Best mix

5. Gas analysis

6. Run Times and Decompression Schedules

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Dive Planning

7. Gas required for:• Descent phase.• Bottom phase.• TTFS phase.• Decompression phase.• What the remaining pressure will be at the end of the bottom phase.

Remember, PSAI refers to this as the required “ascent gas”.• Oxygen exposure and total CNS% after surfacing (use the PSAI

tracking sheet).• When to switch gases during descent and ascent.• On some dives you’ll have to keep up with actual “run times” for all

the phases. This is best done on a wrist slate. Run time management is very important. We’ll cover it during the course so you’ll know how to list it on your dive slate and how to keep up with the “run times.”

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Instructor Dive Plan

A. Depth, BT, Ascent PSI/BAR, Deco. (On slate)

B. Site description.

C. Hand and light signals.

D. Descent procedure.

E. Emergency compass heading.

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Instructor Dive Plan

F. Ascent procedure:– Be prepared for quick gas shift.– Execute gas shift without being told.– Be prepared for alternate decompression schedule if

instructor points to it.

G. Chamber location, directions and protocol.

H. Use applicable sections of PSAI ERD dive planning sheet.

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Shallow Water Skills 12 msw (40 fsw)• While stationary, on a platform or another

shallow area of the dive site:– Remove and replace (R&R) stage cylinders.– Repeat this skill with a flooded mask.– Perform gas shutdowns.– If equipped with an isolator valve, turn it off.– Turn off and breathe down primary regulator, go to

backup, then turn primary back on, turn off back up and go back to primary. Turn backup unit on and, if applicable, open up isolator valve.

– Hook up and deploy a SMB.

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Shallow Water Skills 12 msw (40 fsw)• While hovering, using BCD to maintain

neutral buoyancy:– R&R stage cylinders.– Repeat gas shut down drills, this will be the above

listed on previous slide.– While swimming, remove the first stage cylinder

and stage it on a fixed location, continue swimming and remove the second cylinder and stage it. Then replace each one while continuing to swim, maintaining buoyancy and swim pace.

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Shallow Water Skills 12 msw (40 fsw)• While swimming, switch to and breathe

from each stage cylinder:– Turn the stage cylinder on, access the second stage,

purge, switch to, and breathe from it.– Switch back to your primary unit, turn stage unit off

and secure the second stage.

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Shallow Water Skills 12 msw (40 fsw)• Flood your mask, start exhaling and swim horizontally, at

least 9 m (30'), to your buddy and begin sharing air. After three breaths continue sharing gas and swim horizontally for at least 30 m (100'), then return to your unit.

• From a depth of 9 m (30'), deploy a DSMB.• Descend to 30 m (100') and ascend to 3 m (10') sharing air.

This may be with the ERDI or another diver. This will be determined later. When sharing air, be sure to maintain the proper ascent rate, with the donor keeping physical contact with the recipient. The main objective of this skill is to show just how difficult it can be under controlled conditions. Under stress it’s even more difficult.

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Deep Water Skills

• Remove and replace both stage cylinders at a depth of 30 m (100'). Cylinders must be replaced on the proper side, with the hot mix hooked up on the diver’s right side if this is a PSAI training dive.

• Be prepared to do an unplanned skill at depth, to check your inert gas narcosis level against the same skill, when doing a Trimix dive later.

• If this skill wasn’t done during the shallow water skills session, share gas from 30 m (100') up to a predetermined depth, using your buddy’s alternate gas source, maintaining buddy eye contact and the proper ascent rate.

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Deep Water Skills

• Deploy a SMB from a depth of 9 m (30'), in less than three minutes, while maintaining neutral buoyancy. This will be done after any required decompression.

• Deploy a SMB from a depth of 18 m (60'), after any required decompression, and then reel up to 9 m (30') while resting hands on the reel, using the BCD to maintain neutral buoyancy.

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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• Overhead Sidemount Diving• Diver Propulsion Vehicle (DPV)

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COME BACK ALIVE

“A mountain has not been climbed successfully until the climber comes back down alive. The true explorers always return to tell where they have been.....”

Lord Hunt, Leader, 1953 Everest Expedition.

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Welcome!

As you venture forth as a certified PSAI Trimix Diver possessing the superior training of PSAI!

1 © 2005 The Professional Scuba Association International PSAI Professional Scuba Association...

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Transcript of 1 © 2005 The Professional Scuba Association International PSAI Professional Scuba Association...