© 2006 The Professional Scuba Association International Advanced Nitrox Program PSAI Professional...

™© 2006 The Professional Scuba Association International

Advanced Nitrox Program

PSAIProfessional Scuba Association International

™

PSAIProfessional Scuba Association International

™3 © 2006 The Professional Scuba Association International

Overview• Module 1

– What is Nitrox diving?• Module 2

– Benefits of Nitrox– Problems Associated with Nitrox Diving– Decompression Sickness– Partial Pressures– Oxygen Clock

• Module 3– The Physics and Math of Nitrox– Depth to ATA, T-formula, EAD concept

• Module 4– The Production of Nitrox– Nitrox Equipment– Gas Analysis


Nitrox in Relation to Other PSAI Courses

• Narcosis Management– Equipment considerations and safety guidelines– Inert gas narcosis– Gas planning

• Nitrox and Advanced Nitrox– Math and physics to use Nitrox

• Extended Range Nitrox– Advanced dive planning– Decompression diving– Gas switching techniques

• Trimix– Helium based diving


What is Nitrox Diving?

• Breathing mixture of nitrogen and oxygen. • Gas mixtures containing oxygen

concentrations above 21% are referred to as Nitrox.

• Other terms: Enriched air, oxygen enriched air, oxygen enriched air Nitrox, enriched air Nitrox and Safe Air.

• Depth limits of a particular Nitrox mix are determined by its oxygen content.


Relationship of Theoretical Basic Concepts in Deep Diving

Nitrox Basic concepts• Nitrox I = 32%• Nitrox II = 36%• PPO2 1.4 / 1.6• Decompression gas(es) for

accelerated decompression

Other concepts in the picture are topics for the Extended Range EANx course.

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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On

gass

ing

zone

Off

gass

ing

zone


Benefits of Nitrox

• All dives are actually decompression dives. – Descend, our bodies undergo compression – Ascend, we are decompressing our bodies

• No stop dives: increased allowable bottom time by reducing the nitrogen content and increasing the oxygen.

• If decompression stops are required, using Nitrox can reduce the decompression stop times.

• Using Nitrox can make the diver feel better and have less fatigue, thus less decompression stress.


Problems Associated with Nitrox Diving

• Nitrox like any other diving gas imposes specific risks:– Perception of Nitrox as a gas for deep diving– Lack of knowledge– Lack of Nitrox dive planning– Improperly marking cylinders– Content not matching with markings– Using non-Oxygen compatible equipment

• Leaking/bursting O-rings• Risk of explosion



• Oxtox:– Central nervous system oxygen toxicity (CNS

Oxtox)• Seizures• Depth and time limits to reduce the risks• Individual tolerance for Oxtox is unpredictable

– Pulmonary oxygen toxicity• Gas breaks

– Cylinder contents vs. gas markings• Gas analysis



• Hyperoxia– An increase in oxygen supplied to the body

tissues– Not a consideration with recreational air diving– Can lead to CNS Oxtox– Time/dose related



• Hypoxia– Failure of the cells to receive or utilize oxygen

to sustain normal function– Uncommon in Nitrox diving, a consideration in

Trimix diving and rebreather diving



• Decompression sickness– Potential problem for most forms of diving– Caused by inert gases that can not be metabolized– Nitrox will reduce the amount of nitrogen absorbed

• When dived on air tables or computers can add safety• If Nitrox tables are used, risk of DCS remains about the same

– Same safety procedures that apply to air diving are recommended for Nitrox diving• Observing depth and time limits• Slow ascent rates• Performing safety stops


Methods of Reducing the Risk of DCS

1. Discourage people with physical disabilities, which may cause poor circulation, from participating in an extended range dive.

2. Ensure that each diver is in good physical condition and properly hydrated.

3. Prepare a thorough dive plan and follow the plan: “Plan Your Dive ~ Dive Your Plan!”

4. Don’t deviate from the appropriate decompression schedules.


Factors Predisposing Divers to DCS

• Exertion– As circulation increases nitrogen absorption increases

(and vice versa)• Dehydration

– Reduces the efficiency of the circulatory system– Caffeine (coffee, tea, energy drinks) and alcohol will cause

dehydration also when consumed after the dive– Breathing dry air and being compressed increases dehydration – Drink large quantities of liquids before the dive

• Physical condition– Reduced circulatory efficiency (age, fatigue, obesity, drugs...)– Thermal stress

• Altitude– Follow standard altitude diving practices– Take the PSAI Air/ EANx Altitude diving course


Factors Predisposing Divers to Oxtox

• Overexertion– Swimming, currents– Hard breathing regulators, increased depths, tight fitting equipment

(increasing breathing resistance) – CO2 buildup (hypercapnia) acts as a catalyst to Oxtox, DCS & narcosis

– On strenuous dives, plan for reduced partial pressure of oxygen and control CO2 excess

• Thermal stress– A decrease in core temperature predisposes a diver to Oxtox

• Individual susceptibility– e.g.- Changes in mental state leading to a change in breathing rate

• Drugs– Combined effect of drugs and PPO2


Signs and Symptoms of Oxtox• Convulsion

– Most serious problem of Oxtox, creating spasms– If your buddy has a convulsion, keep them at depth until the convulsion

ends and then bring to the surface, avoiding lung expansion problems• Nausea

– Appears to be the most commonly noticed symptom• Muscular twitching

– Normally in facial muscles such as lips, cheeks, under the skin• Auditory disturbances

– Ringing ears• Visual Disturbances

– Tunnel vision, dazzle, halo vision, loss of vision• Dizziness

– Varies from light headiness to vertigo• Anxiety and confusion

NOTE: Many of the signs and symptoms are similar to other diving maladies!


Partial Pressures

• Daltons law – The total pressure exerted by a mixture of gases is the sum of the pressures that would be exerted by each gas if it alone were present and occupied the total volume.– PPO2 = Partial pressure of Oxygen

– Oxygen exposure limits• PPO2 1.6 ATA for ideal conditions with short or no

decompression times• PPO2 1.4 ATA for less than ideal conditions or dives with long

decompression obligations


Partial Pressure and Exposure Time Limits

PO2 Single Exposure Limit 24 Hour Exposure limit

BAR Minutes Hours:Minutes Minutes Hours:Minutes

1.6 45 0:45 150 2:30

1.5 120 2:00 180 3:00

1.4 150 2:30 180 3:00

1.3 180 3:00 210 3:30

1.2 210 3:30 240 4:00

1.1 240 4:00 270 4:30

1.0 300 5:00 300 5:00

0.9 360 6:00 360 6:00

0.8 450 7:30 450 7:30

0.7 570 9:30 570 9:30

0.6 720 12:00 720 12:00

Exceptional Exposure Limits

2.0 30 0.5

1.9 45 0.75

1.8 60 1:00

1.7* 75 1:25

1.6 120 2:00

1.5 150 2:30

1.4 180 3:00

1.3 240 4:00


Partial Pressure and Exposure Time Limits Guidelines

1. When conducting a series of repetitive dives, the total oxygen partial pressure time for all the combined dives must not exceed the single daily exposure time limit.

2. If either a single dive or multiple dives reach or exceed the single exposure limit, the diver must spend a SIT of at least two hours.

3. If a single dive or multiple dives, within a 24-hour period, reach the maximum 24-hour limits, the SIT must be at least 12 hours.

4. During the SIT you must breathe nothing other than air. These guidelines should be followed because oxygen doses are cumulative.


The Oxygen Clock

A formula used to measure the allotted oxygen exposure limit:

CNS exposure% = (PO2 exposure in min/PO2 exposure limit in min) × 100%

Lets practice:

1. What is the CNS% at 1.6 PPO2 for a 25 minute exposure?

2. What is it at 1.5 PPO2 for a 30 minute exposure?

3. If 35 minutes were spent at 1.23 PPO2 what would the CNS% be?

In a multi-level dive including decompression dives, add the exposures to get the total exposure.


The History of Decompression Diving

Since 1962

PSAI has taught proven

decompression techniques.



• Symptoms of DCS (the bends) were noted during the 1800’s among people working in various hyperbaric environments:– Pressurized mines– Caisson workers– Early commercial and military divers



• The work of such pioneering researchers as Paul Bert and John Haldane resulted in:– The first decompression tables– Initial decompression techniques– The early use of oxygen and nitrox for

decompression



• 1950’s– Most recreational divers adopted the use of

military tables, such as the U.S. Navy Tables– Recreational divers used these tables to avoid

decompression dives– Most recreational training agencies adopted the

“no decompression diving rule”



• Late 1950’s to early 1960’s– Hal Watts began to develop techniques for safer

diving at depth– Hal had special tables developed and began a

program of education for deep decompression diving

– Hal founded the Florida State Skin Diving Schools (FSSS) in 1962 which evolved into today’s Professional Scuba Association International (PSAI)



• 1980’s to present– The 1980’s saw the development of non-traditional

dive courses termed “technical diving”– The proven techniques that PSAI had been using

from the beginning easily merged into this next generation of diving activities

– Since the 2000’s PSAI has experienced phenomenal international growth based on a long history of safety, knowledge and integrity


Decompression Physiology

Anyone engaging in decompression diving should have a current medical examination by a qualified medical professional.



• As a diver goes to depth, the nitrogen in their breathing gas is absorbed by the body tissues.

• Unlike oxygen, nitrogen is not used by the body for metabolism and therefore builds up.

• Upon surfacing the ambient pressure is reduced and the excess nitrogen must be eliminated.



• To reduce potential problems from the excess nitrogen the diver must carefully monitor:– Depth– Time– Ascent rate

• Knowing the above, the diver then applies a proven set of decompression tables.



• Surfacing with too much nitrogen in the body may result in this nitrogen coming out of solution in the form of bubbles which may cause:– Pain– Numbness and paralysis– Tissue damage– In extreme cases - death


Respiratory System

http://upload.wikimedia.org/wikipedia/commons/c/c9/Respiratory_system_complete.svg


The Respiratory System

• Mouth and nose• Trachea• Bronchi• Bronchioles• Alveolar ducts• Alveoli


Circulatory System

http://upload.wikimedia.org/wikipedia/commons/e/e5/Diagram_of_the_human_heart_(cropped).svg


Circulatory System

http://upload.wikimedia.org/wikipedia/en/d/db/Alveoli_diagram.png


Decompression Dive Schedules

TABLE 1

No-Decompression Air Dive Table No-Decompression Limits and Repetitive Group Designators for No-Decompression Air Dives

0 - 700 meters Bühlmann ZH-L16B Algorithm

IMPORTANT: The Bühlmann Tables require a 1 minute stop at 3 meters at the end of every no-decompression dive for altitudes of 0 – 700 meters. PSAI recommends 3 to 5 minutes for this final stop.

Depth (msw)

9

12

15

18

21

24

27

30

33

36

39 42 45 48 51 54 57

RG No-Deco Limit

1 min @ 3m stop as mandatory. 130 111 59 44 28 24 18 16 11 10 * * * * * * *

PSAI

25 19 16 14 12 11 10 9 8 7 A

37 25 20 17 15 13 12 11 10 9 B 55 37 29 25 22 20 18 16 11 10 C 81 57 41 33 28 24 D

105 82 59 44 E 130 111 F

G

Intermediate depth - Use next deeper depth



TABLE 2Bühlmann Surface Interval & Repetitive Group Table

ZH-L16B Algorithm (0 - 3000 meters)

The Surface Interval Times are listed in Minutes, except for “0” Hours & Hours to Fly

“0” Hours

Hours to Fly

Beginning Repetitive Group A 2 hours 2 hours

B 20 2 hours 2 hours

Beginning Repetitive Group

C 10 25 3 hours 3 hours

D 10 15 30 3 hours 3 hours

E 10 15 25 45 4 hours 3 hours

F 20 30 45 75 90 8 hours 4 hours

G 25 45 60 75 100 130 12 hours 5 hours

H 50 65 95 130 180 240 340 24 hours 7 hours

K 180 240 300 360 420 480 560 39 hours 14 hours

L 360 420 510 600 720 840 990 48 hours 24 hours

G

F

E

D

C

B

A

Fully Out-Gassed.

Hours Before Flying

Repetitive Group After the Surface Interval

P S A I



TABLE 3

Residual Nitrogen Time Table 0 - 3000 meters

Bühlmann ZH-L16B Algorithm

Depth of next dive msw

9

12

15

18

21

24

27

30

33

36

39

42

45

48

51

54

57

Rep

etiti

ve G

roup

at t

he e

nd o

f th

e su

rfac

e in

terv

al

A 25 19 16 14 12 11 10 9 8 7 7 6 6 6 5 5 5

B 37 25 20 17 15 13 12 11 10 9 8 7 7 6 5 5 5

C 55 37 29 25 22 20 18 16 14 12 11 10 9 8 7 7 6

D 81 57 41 33 28 24 21 19 17 15 14 13 11 10 9 9 8

E 105 82 59 44 37 30 26 23 21 19 17 16 14 13 12 11 10

F 130 111 88 68 53 42 35 30 27 24 21 19 17 16 15 14 13

G 154 137 115 91 72 57 47 40 35 31 27 25 23 21 20 19 18

For an intermediate depth for your repetitive dive - Use next shallower depth.

P S A I


Decompression Dive SchedulesTABLE 4

Air Decompression Table 0 - 700 meters

Bühlmann ZH-L16B Algorithm Depth MSW

Bottom Time

Decompression Stops MSW

Repetitive Group

15 12 9 6 3

33

14 1 D 20 4 E 25 2 7 F 30 4 11 G 35 6 17 G 40 2 8 23 G 45 4 11 28 H 50 5 15 31 H

36

12 1 D 15 3 D 20 2 5 E 25 4 9 F 30 2 5 15 G 35 2 8 23 G 40 5 10 28 G 45 7 15 31 H

39

10 1 D 15 4 E 20 3 7 F 25 2 4 12 G 30 3 7 18 G 35 6 10 23 G 40 2 7 13 29 H

42

9 1 D 12 4 D 15 1 5 E 18 4 6 F 21 2 4 10 F 24 3 6 16 G 27 4 7 19 G 30 2 4 9 24 G 33 2 6 10 26 G 36 3 7 13 28 H

P S A I



TABLE 5



TABLE 6


Planning a Decompression Dive

In order to reduce the probability of DCS,

a decompression dive must be thoroughly planned and accurately executed.

Nothing should be left to chance.


Planning a Decompression Dive

• Consider pre-dive conditions:– Weather– Water– Equipment– Health– Mental attitude


Dive Profile

• The planned depth and the planned run time of the dive must be known.

• The decompression gas and depth at which this gas will be used must be considered.

• The decompression schedule and required stop times a depths must be calculated by either:– PSAI approved tables.– PSAI approved computer generated tables.


Dive Profile

• Contingency decompression schedules must be generated:– The next greater time.– The next greater depth.– The next greater time and depth.

• The divers must ensure there is adequate gas to cover these contingencies.


Gas Management

• SCR or Surface Consumption Rate (also referred to as SAC or Surface Air Consumption) is always measured in either Bar or PSI per minute.

• RMV or Respiratory Minute Volume is always measured in liters or cubic feet per minute.


Gas Management

SCR Formula

Metric:

[Bar used divided by dive time] X 10 = Bar used per minute per ATA

Depth + 10

Imperial:

[PSI used divided by dive time] X 33 = PSI used per minute per ATA

Depth + 33


Diving Techniques –Decompression Stops

• Decompression stops must be stable allowing a diver to maintain consistent depth.

• Buoyancy control is critical.• Avoid strenuous work during the stop.• Make sure equipment does not interfere

with blood circulation.• Light movement during the stop helps to

improve circulation in arms and legs.


Diving TechniquesStable and Safer Decompression

• Decompression may be done:– In contact with an anchor line or ascent line.– Using an SMB.– Holding on to a wall in a quarry or sinkhole.– Using a weighted shot line.– Using a pre-stationed platform.– Using a decompression trapeze.


Diving Techniques – Lowering DCS Risk

• Stay well hydrated – extremely important.• Avoid:

– Alcoholic drinks – before or after deco diving– Excessive caffeine– Hot showers or hot tubs– Excessive exertion– Smoking


Omitted or Interrupted Decompression

• Never take a diver back underwater who exhibits ANY symptoms of DCS.

• For divers who exhibit DCS symptoms:– Place on oxygen.– Rehydrate.– Maintain body temperature.– Get them to a medical facility or a recompression

chamber facility.



• For short time misses, according to the US Navy, the most common solution is to place the diver on oxygen (30 minutes is MINIMUM) and monitor their condition.

• Further diving is to be suspended for 24 to 48 hours.



U.S. Navy In Water Treatment (IWT)• If the diver surfaces free of symptoms after an

omitted or interrupted decompression, and can get back into the water within 4 to 5 minutes:– Repeat any stops deeper than 12 MSW (40 FSW).– Multiply the 9, 6 and 3 MSW (30, 20 and 10 FSW )

stops by 1.5 the time of the 3 MSW (10 FSW) stop.



IWT may be potentially hazardous due to:• Weather• Gas supplies• Potential for worsening symptoms underwater• Warmth• Rehydration

In no case should a diver experiencing any symptoms of DCS be returned to the water.


The Use of Nitrox and Oxygen for Decompression

• Advantages:– Accelerates nitrogen out-gassing.– Shortens the decompression obligation.



A certified PSAI Advanced Nitrox Diver

may choose to use any nitrox mixture up to 100% oxygen as a decompression gas.



• Concerns:– You must accurately calculate the Maximum

Operating Depth (MOD) of your bottom mix and deco gas.

– The MOD must never be exceeded.– You must track the oxygen exposure (“Oxygen

Clock”) for the entire dive (including the bottom time and decompression stops) and not exceed the oxygen toxicity limits.



• Special tables must be used to accelerate decompression using nitrox or oxygen.– Commercially available tables with set

decompression mixtures.– Tables generated by custom software, allowing

the diver to input specific mixtures for both bottom mix and decompression mixtures.


Oxygen for Decompression

• Oxygen cylinders must be clearly marked and identified.

• The regulators and cylinders must be oxygen cleaned and serviced.

• Oxygen must not be used deeper than 6 meters (20 feet).


Equipment

• Primary Cylinders:– Must allow a sufficient gas supply for the

planned dive and gas management rules that apply.

– Primary gas supply should have a dual outlet.• Large volume singles should be equipment with a

“Y” or “H” valve.• Twin sets should have a dual outlet manifold with

an isolation valve.• DIN outlets are highly recommended.


Equipment

• Cylinders (Deco or Stage Bottles):– Must be properly configured for a clean and low

profile.– Must have a sufficient gas supply for all

contingency plans.– DIN valves are recommended, compatible with

those of the primary gas supply.


Equipment

• Regulators:– High quality high performance regulators are a

must.– Regulators must be regularly serviced

according to the manufacturer’s specifications.– Primary regulators should have the same valve

connection as the deco regulators (DIN is recommended).


Equipment

• Regulators:– Primary regulators do not need to have an

octopus since there are two primary regulators.– One primary regulator should have a 2 to 3

meter (5 to 9 foot) hose for one second stage.– The deco regulators have no need of an octopus.– All regulator hoses should be neatly configured

and clean (nothing dangling or no loops hanging outward from the diver’s body).


Equipment

• Buoyancy Control Device (BCD):– The BDC should have ample lift for the diver’s

configuration (keeping in mind the heavy primary cylinders and deco bottles).

– Wetsuit divers should have a dual bladder BCD in case of bladder or inflator hose failure.


Equipment

• Surface Marker Buoy (SMB):– Should be colored to be easily visible at the surface.– The diver’s name (large letters) should be on the SMB.– A lift capacity of 20 to 25 Kg (50 lb) is minimum.– Appropriate reel or spool should be used with SMB.– Exhaling into the SMB is the most common way to

inflate.

Never purge your regulator into an SMB to inflate as this may result in freeze up and free flow!


Equipment

• Jonline/Decoline:– A jonline is handy to allow a diver to move off

an anchor line or ascent line being used by many dive teams.

– Generally it is at least a 0.7 cm (¼ inch) diameter line.

– Normally the jonline is attached to the anchor or ascent line with a special clip.


Equipment

• Depth and Time Monitors:– Decompression dives should have at least two

systems for monitoring depth and time.• A dive computer backed up with a depth gauge and

some type of bottom timer or watch.• Two dive computers.

– The diver should always carry a backup set of tables in the event of a computer failure.


Equipment

• Environmental Protection:– Wetsuits are generally used in warm waters.

• They must fit well yet not be too tight.• Hooded vests are important for long exposures.

– Dry suits are the choice of many decompression divers.• Not affected by the depth of the dive.• Allow for greater warmth due to cold water or

longer exposure.


Equipment

• Line Cutting Devices:– At least two line cutting devices should be

standard equipment for decompression diving:• “Z-knife”.• Dive scissors.• Traditional (small variety) dive knife.


Equipment

• Lights:– Depending on dive conditions and visibility a

decompression diver may require an underwater light. Some conditions require a minimum of two or more lights.

– Large lights are handy during the bottom phase of the dive.

– Smaller lights are handy for reading dive schedules, gauges or computers.


Equipment

• Other Equipment:– Backup mask (to be carried underwater).– Signaling device:

• Audio signaling device.• Dye marker.• Flares.• GPS or EPIRB.


The Physics and Math of Nitrox

• Convert depth in meters (feet) to ATA (Atmosphere Absolute)

• Convert ATA to MSW (FSW) • Convert MSW to MFW (FSW to FFW)• Best mix formula• MOD formula (Maximum operating depth)• EAD formula (Equivalent air depth)


Converting Depth to ATA andATA to Depth - Metric

• Always use MSW– 10 meters of sea water exert the pressure of 1ATA which is

1bar– For freshwater it takes 10.37 meters to equal 1ATA– 10 MSW = 1 ATA = 10.37 MFW (depending on salinity)

ATA = (MSW/10) + 1 ATA= (MFW/10.3) + 1

MSW = (ATA - 1) × 10 MFW = (ATA - 1) × 10.3

How many msw is 4.5 ATA?

How many msw is 5.0 ATA?


Converting Depth to ATA andATA to Depth - Imperial

• Always use FSW– 33 feet of sea water exerts the pressure of 1 ATA which is

1bar– For freshwater it takes 34 feet to equal 1 ATA– 33 FSW = 1 ATA = 34 FFW (depending on salinity)

ATA = (FSW/33) + 1 ATA= (FFW/34) + 1

FSW = (ATA - 1) × 33 FFW = (ATA - 1) × 34

How many fsw is 4.5 ATA?

How many fsw is 5.0 ATA?


The ‘T’ Formula

• Used to solve:– The PPO2 of a gas– The best mixture for a given dive– Determine the MOD of a gas mixture

Pg Pg= pressure of gas in ata (PPO2)

Fg P Fg= fraction of gas in % (Ean%)

P= ambient pressure (MOD)

1. What is the PPO2 of 32% Nitrox at 40 MSW (130 FSW)?2. What is the best mix for a dive to 30 MSW (100 FSW), the water

is calm; however there is a strong current?3. What is the MOD of 36% Nitrox under ideal conditions?


The Equivalent Air Depth (EAD)

• Compares the nitrogen partial pressure of a Nitrox mixture at a specific depth to that of air depth equivalent.

• Very useful in determining the no-stop limits using the air tables.Metric formula EAD = [(FN2 / 0.79) × (D msw + 10)] – 10

Imperial formula EAD = [(FN2 / 0.79) × (D fsw + 33)] – 33

1. What is the EAD of 32% Nitrox at 30 msw (100 fsw)?

2. What air table would be used in that case?

3. What would the no-stop limit be?

4. What would the no-stop gain be?


Moving Between Table

• Switching between air and Nitrox table must be done on tables generated with the same algorithm where the RG’s all are equivalent. PSAI has such tables available.

• The RNT (residual nitrogen time) table must be that of the gas to be used on the next dive.

• The no-stop time limit will be based on the gas to be used on the repetitive dive.


Nitrox Dive Planning

A dive is planned to 33 msw (110 fsw). The current is very strong and the water is extremely cold.1. What is the best mix?

2. What is the EAD?

3. What is the no-stop limit?

4. If the maximum allowable bottom time is spent, what is the CNS%?

5. After three hours of SIT (surface interval time), what is the repetitive group?

6. If another dive was planned to 30 msw (100 fsw) using Nitrox 32%, what would the no stop limit be?


Production of Nitrox

• Partial pressure blending:– Put oxygen to cylinder.– Top off with oxygen compatible air.– Use only oxygen cleaned cylinders, valves and hoses.– Use of Nitrox compatible lubricants in compressors.– Most cost efficient and common blending system.

• Continuous blending system:– Oxygen is metered and injected into air flow.– Suitable only for mixes below 40%.– Available from specialist shops.– Can be used to prepare Trimix mixtures.


Nitrox and Equipment

• Equipment that is exposed to 40% or higher oxygencontents requires special cleaning and replacement parts.

• Always follow manufacturers recommendations.• When partial pressure blending is used, cylinders and

valves must be oxygen cleaned.• When over 40% mixtures are used, the whole system must

be oxygen compatible.– Regulators– High pressure hoses– Cylinders– Valves– Gauges


Gas Analysis

• Oxygen content of all Nitrox mixtures must be analyzed by user upon purchase and just prior to diving.

• The mixture must be within +-1% of the target mix otherwise a refill or a new dive plan is required.– Higher content predisposes to Oxtox– Lower content predisposes to DCS

• The cylinders must be labeled with content and MOD markings sticker.

• Decompression bottles should also have 2" visible markings of MOD on the side.


Safety Review

• 1.6 is the maximum PPO2 to be used on any dive, and only under ideal conditions. Generally, a PPO2 of no greater than:− 1.4 ATA should be used for planning dives with less

than ideal conditions.

− The PPO2 should be further reduced as deemed necessary.

• As stated before either the 1.4 or the 1.6 ATA can be used. After this course, you’ll decide which one you are most comfortable with.


Safety Review

• The parameters of this certification are single tank no-stop dives using various Nitrox mixtures and up to 100% O2 for a safety stop.

• You should take into consideration any factors that may predispose you to Oxtox or DCS.

• The PPO2 and no-stop time limits must be adhered to.

• When conducting repetitive dives, you must follow the guidelines in this manual pertaining to required surface intervals.


Safety Review

• You should be familiar with the signs and symptoms of DCS and Oxtox, as well as knowing how you can reduce the risks.

• To safely dive Nitrox you need to understand and be able to work with all the formulas that were covered in class or have the printed charts and know how to use them.

• When switching between Nitrox mixtures on repetitive dives, the residual nitrogen time (RNT) table used must be the one pertaining to the gas to be used on the repetitive dive.

• Never attempt to mix your own “home brew” of Nitrox.


Safety Review

• Cylinders are to be dedicated for Nitrox only and they should have contents labels that specify the oxygen and nitrogen percentages and the MOD. Once dedicated, they should be filled with only oxygen compatible air to avoid contamination.

• Nitrox should always be analyzed prior to its use. The end user should personally analyze the gas or witness the process. You should have your own analyzer.


Summary

• Understand the problems associated with Nitrox diving.

• Know the factors predisposing to Oxtox.• Know the factors predisposing to DCS.• Know and understand how to use the ‘T’-formula.• Understand how to do the Nitrox dive planning.• Remember always to check the cylinder(s)

contents and mark the cylinders.


PSAI Technical Diving Programs• Cave • Nitrox • Trimix • Cavern • Dry Suit • Rebreather • Gas Blender• Full Face Mask• Twin Set Diving• Side Mount Diving• Advanced Nitrox • Advanced Wreck: Overhead / Penetration• Narcosis Management • Technical Dive Rescue: PSAI TEAM Program™• Advanced Gas Blender• Extended Range Nitrox • Oxygen Service Technician• Visual Inspection Technician• Overhead Sidemount Diving• Diver Propulsion Vehicle (DPV)


Welcome!

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

© 2006 The Professional Scuba Association International Advanced Nitrox Program PSAI Professional...

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