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Technical diver during a decompression stop.Technical diving (sometimes referred to as Tec diving) is a form of scuba diving that exceeds the scope of recreational diving (although the vast majority of technical divers dive for recreation and nothing else). Technical divers require advanced training, extensive experience, specialized equipment and often breathe breathing gases other than air or standard nitrox.[1]

The concept and term 'technical diving' are both relatively recent advents,[note 1] although divers have been engaging in what is now commonly referred to as technical diving for decades. The term "technical diving" was first coined by Michael Menduno, editor of (now defunct) diving magazine AquaCorps in 1991.[2]

Contents

[hide] 1 Definition of 'technical diving'

o 1.1 Depth o 1.2 Inability to ascend directly

1.2.1 Decompression stops 1.2.2 Physical ceiling

o 1.3 Extremely Limited Visibility o 1.4 Gas mixes

1.4.1 "Deep air"/extended range diving 2 Equipment 3 Training 4 See also 5 References 6 Footnotes

7 External links

[edit] Definition of 'technical diving'

There is some level of professional disagreement as to what the term should encompass.[3][4][5] It was not that many years ago that NITROX diving was considered "technical"; however today NITROX is not normally considered technical. Some say that technical diving is any type of SCUBA that is considered higher risk than conventional recreational diving. However, some advocate that this should include penetration diving (as opposed to open-water diving), whereas others contend that penetrating overhead environments should be regarded as a separate type of diving. Others seek to define technical diving solely by reference to the use of decompression.[note 2] Certain minority views contend that certain non-specific higher risk factors should cause diving to be classed as technical diving. Even those who agree on the broad definitions of technical diving may disagree on the precise boundaries between technical and recreational diving.

PADI , the largest recreational diver training agency in North America, defines technical diving as "diving other than conventional commercial or recreational diving that takes divers beyond recreational diving limits. It is further defined as an activity that includes one or more of the following: diving beyond 40 meters/130 feet, required stage decompression, diving in an overhead environment beyond 130 linear feet from the surface, accelerated stage decompression and/or the use of multiple gas mixtures in a single dive."[6]

NOAA defines technical diving in this way: "Technical diving is a term used to describe all diving methods that exceed the limits imposed on depth and/or immersion time for recreational scuba diving. Technical diving often involves the use of special gas mixtures (other than compressed air) for breathing. The type of gas mixture used is determined either by the maximum depth planned for the dive, or by the length of time that the diver intends to spend underwater. While the recommended maximum depth for conventional scuba diving is 130 ft, technical divers may work in the range of 170 ft to 350 ft, sometimes even deeper. Technical diving almost always requires one or more mandatory decompression "stops" upon ascent, during which the diver may change breathing gas mixes at least once."[7] NOAA does not address issues relating to overhead environments in its definition.

The following table tries to set out the broad indicative parameters of what is normally regarded as technical rather than recreational diving.

Technical Diving

Activity Recreational Technical

Deep divingMaximum depth of 40 metres/130 feet[note 3] Below 40 metres/130 feet

Decompression diving [note 4]

No decompression Decompression diving

Mixed gas diving Air and Nitrox Trimix, Heliox, Heliair and Hydrox

Gas switching Single gas usedMay switch between gases to accelerate decompression and/or "travel mixes" to permit descent carrying hypoxic gas mixes

Wreck divingPenetration limited to "light zone" or 30 metres/100 foot depth/penetration

Deeper penetration

Cave diving

Penetration limited to "light zone" or 30 metres/100 foot depth/penetration[note 5]

Deeper penetration

Ice divingSome agencies regard ice diving as recreational diving;PADI others as technical diving.NAUI

RebreathersSome agencies regard use of semi-closed rebreathers as recreational diving;PADI others as technical diving.NAUI

Solo divingRecreational diving requires buddy system

Solo diving[note 6]

[edit] Depth

Diver returning from a 600ft diveTechnical dives may be defined as being either dives to depths deeper than 130 feet / 40 meters or dives in an overhead environment with no direct access to the surface or natural light. Such environments may include fresh and saltwater caves and the interior of shipwrecks. In many cases, technical dives also include planned decompression carried out

over a number of stages during a controlled ascent to the surface at the end of the dive.The depth-based definition is derived from the fact that breathing regular air while experiencing pressures causes a progressively increasing amount of impairment due to nitrogen narcosis that normally becomes serious at depths of 100 feet / 30 metres or greater. Increasing pressure at depth also increases the risk of oxygen toxicity based on the partial pressure of oxygen in the breathing mixture. For this reason technical diving often includes the use of breathing mixtures other than air.These factors increase the level of risk and training required for technical diving far beyond that required for recreational diving. This is a fairly conservative definition of technical diving.

[edit] Inability to ascend directly

Technical dives may alternatively be defined as dives where the diver cannot safely ascend directly to the surface either due to a mandatory decompression stop or a physical ceiling. This form of diving implies a much larger reliance on redundant equipment and training since the diver must stay underwater until it is safe to ascend or the diver has left the overhead environment.

[edit] Decompression stops

Free floating decompression stop.A diver at the end of a long or deep dive may need to do decompression stops to avoid decompression sickness, also known as the "bends". Metabolically inert gases in the diver's breathing gas, such as nitrogen and helium, are absorbed into body tissues when breathed under high pressure during the deep phase of the dive. These dissolved gases must slowly be released from body tissues by pausing or "doing stops" at various depths during the ascent to the surface. In recent years most technical divers have greatly increased the depth of the first stops, so as to reduce the risk of bubble formation before the [more traditional] long shallow stops. Most technical divers breathe enriched oxygen breathing gas mixtures such as nitrox during the beginning and ending portion of the dive. To avoid nitrogen narcosis while at maximum depth it is common to use trimix which adds a percentage of helium replacing nitrogen to the diver's breathing mixture. Pure oxygen is then used during shallow decompression stops to reduce the time needed by the diver to effectively rid themselves most of remaining excess inert gas in their body tissues and reducing the risk of "the bends." Surface intervals are usually required to prevent the residual nitrogen from building up to dangerous levels on subsequent dives.

[edit] Physical ceiling

These types of overhead diving can prevent the diver surfacing directly: Cave diving - diving into a cave system. Deep diving - diving into greater depths. Ice diving - diving under ice. Wreck diving - diving inside a shipwreck.

[edit] Extremely Limited Visibility

Technical dives in waters where the diver's vision is severely impeded by low-light conditions, caused by silt or depth, require an elevated level of aptitude because of the knowledge and skill required to operate in such an environment, and because visibility impairments are often caused by moving water currents. The combination of low visibility and swift current make these technical dives extremely risky to all but the most skilled and well-equipped divers.[citation needed]

[edit] Gas mixes

Technical dives may also be defined by the use of hypoxic breathing gas mixtures other than air such as trimix, heliox, and heliair. This definition is derived from the fact that breathing a mixture with the same oxygen concentration as is found in air (roughly 21%) at depths greater than 180 feet / 55 meters results in a very rapidly increasing risk of severe symptoms of oxygen toxicity. The first sign of oxygen toxicity is usually a convulsion without warning. This convulsion usually results in a fatal accident, as the regulator falls out and the victim drowns. Sometimes the victim may get warning symptoms prior to the convulsion. These can include visual and auditory hallucinations, nausea, twitching (especially in the face and hands), irritibility and mood swings and dizziness. Increasing pressure due to depth also causes nitrogen to become narcotic, resulting in a reduced ability to react or think clearly (see Nitrogen narcosis). By adding helium to the breathing mix, divers can reduce these effects, as helium does not have the same narcotic properties at depth. These gas mixes can also lower the level of oxygen in the mix to reduce the danger of oxygen toxicity. Once the oxygen is reduced below 18% the mix is known as a hypoxic mix as it doesn't contain enough oxygen to be used safely at the surface.Nitrox is another common gas mix, and while it is not used for deep diving, it decreases the build up of nitrogen within the diver's body by increasing the percentage of oxygen. This reduces the nitrogen percentage, as well as allowing for a greater number of multiple dives vs "standard" air. The depth limit of Nitrox is governed by the percentage of oxygen used, as there are multiple oxygen percentages available in nitrox. Further training and knowledge is required in order to safely use and understand the effects of these gases on the body in a diving situation.

[edit] "Deep air"/extended range diving

One of more divisive subjects in technical diving relates to using compressed air as a breathing gas on dives below 130 feet/40 meters.[8] Whilst the largest technical diver training agencies still promote and teach such courses (TDI[9], IANTD and DSAT/PADI), there is an increasingly vocal minority (NAUI Tec, GUE, UTD) which argues that diving deeper on air is unacceptably risky, and argue that helium mixes should be used for dives beyond a certain limit (100 - 130 feet, depending upon agency). Such courses used to be referred to as "deep air" courses, but are now commonly called "extended range" courses.Deep air proponents base the proper depth limit of air diving upon the risk of oxygen toxicity. Accordingly, they view the limit as being the depth at which partial pressure of oxygen reaches 1.4 ATA (which occurs at about

186 feet/50 metres). Helitrox/triox proponents argue that the defining risk should be nitrogen narcosis, and suggest that when the partial pressure of nitrogen reaches approximately 4.0 ATA (which occurs at about 125 feet/38 meters) helium is necessary to offset the effects of the narcosis.DAN does not formally reject deep air diving per se, but it is keen to point out a number of additional risks which such diving involves.[10]

[edit] Equipment

Technical diver with decompression gases in side mounted stage cylinders.Technical divers may also use various forms of less common diving equipment to accomplish their goals. Typically technical dives involve significantly longer durations than average recreational scuba dives. As decompression stops act as a virtual overhead, preventing a diver with a problem from surfacing immediately, there is a need for redundant equipment. Technical divers usually carry at least two tanks, each with its own regulator. In the event of a failure, the second tank and regulator acts as a back-up system. Technical divers therefore increase their supply of available breathing gas by either connecting multiple high capacity diving cylinders and/or by using a rebreather. The technical diver may also carry additional cylinders, known as stage bottles, to ensure adequate breathing gas supply for decompression with a reserve for bail-out in case of failure of their primary breathing gas. The stage cylinders are normally carried using an adaptation of a sidemount configuration.

[edit] Training

Technical diving requires specialised equipment and training. There are many technical training organisations: see the Technical Diving section of List of diver training organizations. Technical Diving International (TDI), Global Underwater Explorers (GUE), International Association of Nitrox and Technical Divers (IANTD) and National Association of Underwater Instructors (NAUI) seem to be popular as of 2009. Recent entries into the market include Unified Team Diving (UTD), and Diving Science and Technology (DSAT), the technical arm of Professional Association of Diving Instructors (PADI). The Scuba Schools International (SSI) Technical Diving Program (TechXR - Technical eXtended Range) was launched in 2005.[11]

British Sub-Aqua Club (BSAC) training has always had a technical element to its higher qualifications, however it has recently begun to introduce more technical level Skill Development Courses into all its training schemes, by introducing technical awareness into its lowest level qualification of Ocean Diver, for example, nitrox will become mandatory. It has also recently introduced trimix qualifications and continues to develop closed circuit training.

[edit] See also

Breathing gas Carbon dioxide poisoning Diving hazards and precautions Oxygen toxicity Rebreather Solo diving Trimix

[edit] References

1. ̂ Richardson, Drew (2003). "Taking 'tec' to 'rec': the future of technical diving". South Pacific Underwater Medicine Society Journal 33 (4). http://archive.rubicon-foundation.org/8125. Retrieved 2009-08-07.

2. ̂ Bret Gilliam. "Deep Diving". http://books.google.vg/books?id=HVbjgdorRXAC&pg=PT1&lpg=PT1&dq=bret+gilliam+deep+diving&source=bl&ots=TjUeAttHoB&sig=hoMQ-34epCgOSWdsCj3doJxGwN4&hl=en&ei=3omuSrzJJp6CtgeR-6nzBw&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=&f=false. Retrieved 2009-09-14. at page 15.

3. ̂ Gorman, Des F (1992). "High-tech diving". South Pacific Underwater Medicine Society Journal 22 (1).

4. ̂ Gorman, Des F (1995). "Safe Limits: A International Dive Symposium. Introduction.". South Pacific Underwater Medicine Society Journal 25 (1). http://archive.rubicon-foundation.org/6425. Retrieved 2009-08-07.

5. ̂ Hamilton Jr, RW (1996). "What is technical diving? (letter to editor)". South Pacific Underwater Medicine Society Journal 26 (1). http://archive.rubicon-foundation.org/6266. Retrieved 2009-08-07.

6. ̂ PADI, Enriched Air Diving, page 91. ISBN 978-1-878663-31-3 7. ̂ " Technical Diving " . NOAA. February 24, 2006.

http://oceanexplorer.noaa.gov/technology/diving/technical/technical.html. Retrieved 2008-09-25.

8. ̂ "Deep Air IS Stupdity". http://www.bluebeyond.com.au/modx/bluebeyond-dive-deep-air-is-stupidity.html. Retrieved 2009-09-03.

9. ̂ "TDI - Extended Range Diver". http://www.tdisdi.com/index.php?did=80&site=2. Retrieved 2009-09-03.

10. ̂ John Lippmann, DAN. "How deep is too deep?". http://www.diversalertnetwork.org/medical/articles/article.asp?articleid=29. Retrieved 2009-09-03.

11. ̂ "SSI TechXR - Technical diving program". Scuba Schools International. http://www.divessi.com/txr. Retrieved 2009-06-22.

[edit] Footnotes

1. ̂ In his 1989 book, Advanced Wreck Diving, author and leading technical diver, Gary Gentile, commented that there was no accepted term for divers who dived beyond agency-specified recreational limits for non-professional purposes. Revised editions

use the term "technical diving", and Gary Gentile published a further book in 1999 entitled The Technical Diving Handbook.

2. ̂ As most technical diving training agencies point out, references to "decompression diving" is a misnomer, as all dives involve an element of decompression as the diver off-gases. However, the term decompression diving is often used to describe diving which involves one or more mandatory decompression stops prior to surfacing.

3. ̂ Most recreational diving agencies recommend diving no deeper than 30 meters/100 feet, and suggest an absolute limit of 40 m/130 feet.[1]

4. ̂ There is a reasonable body of professional opinion that considers decompression diving to be the sole differentiator for "technical" diving.SSI

5. ̂ Some certification agencies prefer to the term "cavern diving" to cave penetration within recreational diving limits.

6. ̂ Some training agencies regard solo diving within the "recreational" sphere.SDI

[edit] External links

Select publications on technical diving and technical diving history - Hosted by the Rubicon Foundation

RebreatherPro Jill Heinerth's interactive multimedia technical diving site Transitioning to technical diving

[hide] v • d • e

Underwater diving

Types:Scuba diving · Surface supplied diving · Free-diving · Snorkelling · Saturation diving

Specialities:Technical diving · Deep diving · Decompression diving · Mixed gas diving · Wreck diving · Cave diving · Ice diving · Rebreather diving · Solo diving · Altitude diving

Equipment:Diving suit · Scuba set · Rebreather · Dive computer · Diver propulsion vehicle · Mask · Fins · Snorkel · Buoyancy control device

Disciplines:Professional diving · Police diving · Military diving · Underwater photography · Underwater videography

Hazards:

Decompression sickness · Nitrogen narcosis · Oxygen toxicity · Barotrauma · Hyperbaric medicine · Drowning · Shallow water blackout · Deep water blackout · High pressure nervous syndrome · Dysbaric osteonecrosis

[hide] v • d • e

Diving decompression

DivingScuba diving · Recreational diving · Deep diving  · Technical diving · Saturation diving

EquipmentDecompression trapeze · Decompression tables · Recreational Dive Planner · Dive computer · Diving chamber · Jonline · Decompression buoy

Gases Trimix · Nitrox · Oxygen · Air · Gas blending

InjuryDecompression sickness  · Hyperbaric medicine  · Decompression chamber  · Recompression chamber

MiscellaneousDecompression stop · Decompression schedule · Decompression curve · No Decompression Limit · In-water recompression · Deco on the fly  · Ratio decompression

AlgorithmsBühlmann decompression algorithm · Reduced gradient bubble model · Thalmann algorithm · Varying Permeability Model

Retrieved from "http://en.wikipedia.org/wiki/Technical_diving"Categories: Underwater divingHidden categories: All articles with unsourced statements | Articles with unsourced statements from November 2007 | Articles containing potentially dated statements from 2009 | All articles containing potentially dated statements

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Trimix (breathing gas)From Wikipedia, the free encyclopedia

Jump to:navigation, search

Contents

[hide] 1 Mixes

o 1.1 Advantages of helium in the mix o 1.2 Disadvantages of helium in the mix o 1.3 Advantages of reducing oxygen in the mix o 1.4 Advantages of keeping some nitrogen in the mix o 1.5 Naming

2 Blending o 2.1 "Standard" mixes

3 Hyperoxic trimix 4 History of trimix as a diving gas 5 See also

6 References

Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used in deep commercial diving and during the deep phase of dives carried out using technical diving techniques.[1][2]

With a mixture of three gases it is possible to create mixes suitable for different depths or purposes by adjusting the proportions of each gas.

[edit] Mixes

[edit] Advantages of helium in the mix

The main reason for adding helium to the breathing mix is to reduce the proportions of nitrogen and oxygen, below those of air, to allow the gas mix to be breathed safely on deep dives.[1] A lower proportion of nitrogen is required to reduce nitrogen narcosis and other physiological effects of the gas at depth. Helium has very little narcotic effect.[3] A lower proportion of oxygen reduces the risk of oxygen toxicity on deep dives.The lower density of helium reduces breathing resistance at depth.[1][3]

Because of its low molecular weight, helium leaves tissues more rapidly than nitrogen as the pressure is reduced (this is called off-gassing). Because of its lower solubility, helium does not load tissues as heavily as nitrogen.

[edit] Disadvantages of helium in the mix

Helium conducts heat six times faster than air; often helium breathing divers carry a separate supply of a different gas to inflate drysuits. This is to avoid the risk of hypothermia caused by using helium as inflator gas. Argon, carried in a small, separate tank, connected only to the inflator of the drysuit is preferred to air, since air conducts heat 50% faster than argon.[4] Dry suits (if used together with a stabilising jacket) still require a minimum of inflation to avoid "squeezing", i.e. damage to skin caused by pressurizing dry suit folds.Some divers suffer from hyperbaric arthralgia during descent.[5]

Helium dissolves into tissues more rapidly than nitrogen as the ambient pressure is increased (this is called on-gassing). A consequence of the higher loading in some tissues is that many decompression algorithms require deeper decompression stops than a similar decompression dive using air.

[edit] Advantages of reducing oxygen in the mix

Lowering the oxygen content increases the maximum operating depth and duration of the dive before which oxygen toxicity becomes a limiting factor.[1][2][6][7]

[edit] Advantages of keeping some nitrogen in the mix

Retaining nitrogen in trimix can contribute to the prevention of High Pressure Nervous Syndrome, a problem that can occur when breathing heliox at depths below 130 meters (429 feet).[1][8][9][10] Nitrogen is also much less expensive than helium.

[edit] Naming

Conventionally, the mix is named by its oxygen percentage, helium percentage and optionally the balance percentage, nitrogen. For example,

a mix named "trimix 10/70" consisting of 10% oxygen, 70% helium, 20% nitrogen is suitable for a 100-metre (330 ft) dive.The ratio of gases in a particular mix is chosen to give a safe maximum operating depth and comfortable equivalent narcotic depth for the planned dive. Safe limits for mix of gases in trimix are generally accepted to be a maximum partial pressure of oxygen (ppO2—see Dalton's law) of 1.0–1.6 bar and maximum equivalent narcotic depth of 30 to 50 m (100 to 160 ft). At 100 m (330 ft), "12/52" has a PPO2 of 1.3 bar and an equivalent narcotic depth of 43 m (141 ft).In open-circuit scuba, two classes of trimix are commonly used: normoxic trimix—with a minimum PO2 at the surface of 0.18 and hypoxic trimix—with a PO2 less than 0.18 at the surface.[11] A normoxic mix such as "19/30" is used in the 30 to 60 m (100 to 200 ft) depth range; a hypoxic mix such as "10/50" is used for deeper diving, as a bottom gas only, and cannot safely be breathed at shallow depths where the ppO2 is less than 0.18 bar.In fully closed circuit rebreathers that use trimix diluents, the mix can be hyperoxic in shallow water because the rebreather automatically adds oxygen to maintain a specific ppO2.[12] Less commonly, hyperoxic trimix is sometimes used on open circuit scuba. Hyperoxic trimix is sometimes referred to as Helitrox or TriOx.See breathing gas for more information on the composition and choice of gas blends.

[edit] Blending

Gas blending of trimix involves decanting oxygen and helium into the diving cylinder and then topping up the mix with air from a diving air compressor. To ensure an accurate mix, after each helium and oxygen transfer, the mix is allowed to cool, its pressure is measured and further gas is decanted until the correct pressure is achieved. This process often takes hours and is sometimes spread over days at busy blending stations.[13]

A second method called 'continuous blending' is now gaining favor.[13] Oxygen, helium and air are blended on the intake side of a compressor. The oxygen and helium are fed into the air stream using flow meters, so as to achieve the rough mix. The low pressure air is analyzed for oxygen content and the oxygen (and helium) flows adjusted accordingly. On the high pressure side of the compressor a regulator is used to reduce pressure and the trimix is metered through an analyzer (preferably helium and oxygen) so that the fine adjustment to the intake gas flows can be made.The benefit of such a system is that the helium delivery tank pressure need not be as high as that used in the partial pressure method of blending and residual gas can be 'topped up' to best mix after the dive.Drawbacks may be that the increased compressibility of helium results in the compressor over-heating (especially in tropical climates) and that the hot trimix entering the analyzer on the high pressure side can affect the reliability of the analysis. DIY versions of the continuous blend units can be made for as little as $200 (excluding analyzers).[13][14]

[edit] "Standard" mixes

Although theoretically trimix can be blended with almost any combination of helium and oxygen, a number of "standard" mixes have evolved (such as 21/35, 18/45 and 15/55). Most of these mixes originated from filling the cylinders with a certain percentage of helium, and then topping the mix with 32% enriched air nitrox. The "standard" mixes evolved because of three coinciding factors - the desire to keep that equivalent narcotic depth of the mix at approximately 100 feet, the requirement to keep the partial pressure of oxygen at 1.4 ATA or below at the deepest point of the dive, and the fact that many dive shops stored standard 32% enriched air nitrox in banks, which simplified mixing.[15] The use of standard mixes makes it relatively easy to top up diving cylinders after a dive using residual mix - only helium and banked nitrox needs to be used to top up the residual gas from the last fill.

[edit] Hyperoxic trimix

The National Association of Underwater Instructors (NAUI) uses the term "helitrox" for hyperoxic 26/17 Trimix, i.e. 26% oxygen, 17% helium, 57% nitrogen. Helitrox requires decompression stops similar to Nitrox-I (EAN28) and has a maximum operating depth of 44 metres (144 ft), where it has an equivalent narcotic depth of 35 metres (115 ft). This allows diving throughout the usual recreational range, while decreasing decompression obligation and narcotic effects compared to air.[16]

GUE and UTD also promote hyperoxic trimix, but prefer the term "TriOx".

[edit] History of trimix as a diving gas

1919 Professor Elihu Thompson speculates that helium could be used instead of nitrogen to reduce the breathing resistance at great depth.[17] The effects from narcosis was not proven until the salvage of the USS Squalus in 1939.[17] Heliox was used with air tables resulting in a high incidence of decompression sickness so the use of helium was discontinued.[18]

1925 The US Navy begins examining helium's potential usage and by the mid 1920's lab animals were exposed to experimental chamber dives using heliox. Soon, human subjects breathing heliox 20/80 (20% oxygen, 80% helium) had been successfully decompressed from deep dives.

1937 Several test dives are conducted with helium mixtures, including salvage diver's Max "Gene" Nohl's dive to 127 meters.

1939 US Navy used heliox in USS Squalus salvage operation.

1965 First saturation dives using heliox.

1970 Hal Watts performs dual body recovery at Mystery Sink (126 m). Cave divers Sheck Exley and Jochen Hasenmayer use heliox to a depth of 212 meters.

1987 First mass use of trimix and heliox: Wakulla Springs Project. Exley teaches non-commercial divers in relation to trimix usage in cave diving.

1991

Billy Deans commences teaching of trimix diving for recreational diving. Tom Mount develops first trimix training standards (IANTD). Use of trimix spreads rapidly to North East American wreck diving community.

1994 Combined UK/USA team, including leading wreck divers John Chatterton and Gary Gentile, successfully complete a series of wreck dives on the RMS Lusitania expedition to a depth of 100 meters using trimix.

2001 The Guinness Book of records recognises John Bennett as the first scuba diver to dive to 1000 ft, using Trimix.

2005 David Shaw sets depth record for using a trimix rebreather, tragically dying while repeating the dive.[19][20]

Source: "Trimix and heliox diving". February 14, 2002. http://www.techdiver.ws/trimix_eng.shtml. Retrieved 2008-10-07.

[edit] See also

Argox Heliox Hydreliox Hydrox Nitrox

[edit] References

1. ^ a b c d e Brubakk, A. O.; T. S. Neuman (2003). Bennett and Elliott's physiology and medicine of diving, 5th Rev ed.. United States: Saunders Ltd.. pp. 800. ISBN 0702025712.

2. ^ a b Gernhardt, ML (2006). "Biomedical and Operational Considerations for Surface-Supplied Mixed-Gas Diving to 300 FSW.". In: Lang, MA and Smith, NE (eds). Proceedings of Advanced Scientific Diving Workshop (Washington, DC). http://archive.rubicon-foundation.org/4655. Retrieved 2008-08-28.

3. ^ a b "Diving Physics and "Fizzyology"". Bishop Museum. 1997. http://www.bishopmuseum.org/research/treks/palautz97/phys.html. Retrieved 2008-08-28.

4. ̂ "Thermal conductivity of some common materials". The Engineering ToolBox. 2005. http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html. Retrieved March 9, 2010. "Argon:0.016; Air:0.024; Helium:0.142 W/mK"

5. ̂ Vann RD and Vorosmarti J (2002). "Military Diving Operations and Support". Medical Aspects of Harsh Environments, Volume 2 (Borden Institute): p980. http://www.bordeninstitute.army.mil/published_volumes/harshEnv2/HE2ch31.pdf. Retrieved 2008-08-28.

6. ̂ Acott, C. (1999). "Oxygen toxicity: A brief history of oxygen in diving". South Pacific Underwater Medicine Society journal 29 (3). ISSN 0813-1988. OCLC 16986801. http://archive.rubicon-foundation.org/6014. Retrieved 2008-08-28.

7. ̂ Gerth, WA (2006). "Decompression Sickness and Oxygen Toxicity in US Navy Surface-Supplied He-O2 Diving.". In: Lang, MA and Smith, NE (eds). Proceedings of Advanced Scientific Diving Workshop (Washington, DC). http://archive.rubicon-foundation.org/4654. Retrieved 2008-08-28.

8. ̂ Hunger Jr, W. L.; P. B. Bennett. (1974). "The causes, mechanisms and prevention of the high pressure nervous syndrome". Undersea Biomed. Res. 1 (1): 1–28. ISSN 0093-5387. OCLC 2068005. PMID 4619860. http://archive.rubicon-foundation.org/2661. Retrieved 2008-08-28.

9. ̂ Bennett, P. B.; R. Coggin; M. McLeod. (1982). "Effect of compression rate on use of trimix to ameliorate HPNS in man to 686 m (2250 ft)". Undersea Biomed. Res. 9 (4): 335–51. ISSN 0093-5387. OCLC 2068005. PMID 7168098. http://archive.rubicon-foundation.org/2920. Retrieved 2008-04-07.

10. ̂ Campbell, E. "High Pressure Nervous Syndrome". Diving Medicine Online. http://www.scuba-doc.com/HPNS.html. Retrieved 2008-08-28.

11. ̂ Tech Diver. "Exotic Gases". http://www.techdiver.ws/exotic_gases.shtml. Retrieved 2008-08-28.

12. ̂ Richardson, D; Menduno, M; Shreeves, K. (eds). (1996). "Proceedings of Rebreather Forum 2.0.". Diving Science and Technology Workshop.: 286. http://archive.rubicon-foundation.org/7555. Retrieved 2008-08-28.

13. ^ a b c Harlow, V (2002). Oxygen Hacker's Companion. Airspeed Press. ISBN 0967887321.

14. ̂ "Continuous trimix blending with 2 nitrox sticks (English)". The shadowdweller. 2006. http://shadowdweller.skynetblogs.be/post/3924720/continuous-trimix-blending-with-2-nitrox-stic. Retrieved 2008-08-28.

15. ̂ TDI Advanced Gas Blender manual 16. ̂ "NAUI Technical Courses: Helitrox Diver". NAUI Worldwide.

http://www.naui.org/technical_divers.aspx#070. Retrieved 2009-06-11. 17. ^ a b Acott, Chistopher (1999). "A brief history of diving and decompression illness.".

South Pacific Underwater Medicine Society journal 29 (2). ISSN 0813-1988. OCLC 16986801. http://archive.rubicon-foundation.org/6004. Retrieved 2009-03-17.

18. ̂ Behnke, Albert R. (1969). "Some early studies of decompression.". In: the Physiology and Medicine of Diving and Compressed air work. Bennett PB and Elliott DH. Eds. (Balliere Tindall Cassell): 226–251.

19. ̂ Mitchell SJ, Cronjé FJ, Meintjes WA, Britz HC (February 2007). "Fatal respiratory failure during a "technical" rebreather dive at extreme pressure". Aviat Space Environ Med 78 (2): 81–6. PMID 17310877. http://www.ingentaconnect.com/content/asma/asem/2007/00000078/00000002/art00001. Retrieved 2009-07-29.

20. ̂ David Shaw. "The Last Dive of David Shaw". http://www.youtube.com/watch?v=mF4iFJ-G74o. Retrieved 2009-11-29.

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Diving decompression

DivingScuba diving · Recreational diving · Deep diving  · Technical diving · Saturation diving

EquipmentDecompression trapeze · Decompression tables · Recreational Dive Planner · Dive computer · Diving chamber · Jonline · Decompression buoy

Gases Trimix · Nitrox · Oxygen · Air · Gas blending

InjuryDecompression sickness  · Hyperbaric medicine  · Decompression chamber  · Recompression chamber

MiscellaneousDecompression stop · Decompression schedule · Decompression curve · No Decompression Limit · In-water recompression · Deco on the fly  · Ratio decompression

Algorithms Bühlmann decompression algorithm · Reduced gradient bubble model ·

Thalmann algorithm · Varying Permeability Model

Retrieved from "http://en.wikipedia.org/wiki/Trimix_(breathing_gas)"Categories: Breathing gases | Helium

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NAUI Technical Courses

Is technical diving for you? NAUI Technical Courses are designed for divers whose interests include diving beyond traditional recreational limits and specific areas of technical diving. Accordingly, technical diving courses are designed to provide more detailed training than specialty diver courses, and result in more extensive qualifications.

NAUI was the first training agency to certify all levels of diving ranging from traditional recreational training through all levels of technical training. Technical diving is a potentially dangerous activity that requires very special training, equipment and support. NAUI Technical Instructors are trained to not only qualify you for your dive objective, but also to give you a healthy respect for the technical diving environment.

Below are just some of the NAUI Technical Courses available through your local NAUI Technical Training Dive Center. Be sure to ask your NAUI Technical Instructor about previous training or experience you may need and get ready to enter the unique world of Technical Diving!

Cave Diver (Levels I, II and III) Cavern Diver CCR Mixed Gas Diver Closed Circuit Rebreather Diver Decompression Technique Heliair Diver Helitrox Diver Ice Diver Intro to Tech

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Instructor TrainerAaron  Uhl

Mixed Gas Blender and O2 Service Tech Semi-Closed Rebreather Diver Technical Nitrox Diver Technical Support Leader Technical Wreck Penetration Diver Tri-Mix Diver (Levels I and II) Wreck Penetration Diver

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Rebreathers approved for training by NAUI are listed below.

Technical Support Leader

Become a NAUI Technical Support Leader! The Technical Support Leader (TSL) course is designed to train knowledgeable NAUI Divemasters and Assistant Instructors who are also technical divers to act as part of a support team for technical diving and training activities.

A Technical Support Leader provides assistance to teams of technical divers provided diving conditions and methods approximate those in which your TSL training occurs. Your TSL responsibilities might include shuttling of equipment, removal and replacement of staged decompression gases and equipment, rigging and setting up decompression stations and gases and monitoring divers during ascent and staged decompression stops.

To enroll in a TSL course, you must be 18; be certified as a NAUI Technical EANx Diver, NAUI Rescue Diver, Oxygen Provider and NAUI Divemaster or NAUI Assistant Instructor; have assisted with the open water portions of at least two entry-level or continuing education diver courses; and 75 logged dives with 10 dives below 100 fsw / 30 msw, and 15 Nitrox dives.

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Technical EANx Diver

The Technical EANx (Nitrox) Diver course will provide you with the skills and knowledge needed to minimize the risks of utilizing optimal breathing gas EANx mixtures of 25% through 80% (oxygen) for dives to a depth of 130 fsw / 40 msw not requiring stage decompression, using 80% EANx for decompression and 25% to 60% EANx for bottom mix.

Your instructor can combine this course with the Decompression Techniques Diver Course with additional training and dives. You’ll need to be 18 and have a minimum certification of NAUI EANx Diver and Deep Diver (or equivalent) and 50 logged dives with 10 dives on EANx to enroll in the Technical EANx Diver course.

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Helitrox Diver

The Helitrox Diver course teaches you how to plan and execute Helitrox-based dives that may require stage decompression and utilize EANx and/or oxygen for stage decompression. This course is designed to teach you the hazards of utilizing Helium for dives to a maximum depth of 150 fsw / 46 msw that may require stage decompression, utilizing EANx mixtures and/or oxygen during decompression.

During your training, you’ll complete at least four open water dives using a Helitrox mixture (26% oxygen / 17% helium) of which at least one will be a repetitive dive. Your NAUI Technical Instructor may combine your Helitrox course with the Decompression Techniques Diver Course, with additional training and certification dives.

Your studies will include the knowledge necessary to plan and safely execute Helitrox dives including gas needs and requirements, oxygen toxicity limitations, nitrogen narcosis limitations, and emergency planning, including omitted decompression, oxygen toxicity, decompression sickness, and equipment failure.

Topics covered will also include emergency and contingency procedures, entry and descent techniques; inert gas narcosis and oxygen toxicity; variable ascent-rate techniques and deep-stop models; diver trim, ballast and buoyancy compensation; tethered or untethered decompression methods; shore or boat based dive team support and chamber locations; communications and emergency breathing gases; and NAUI Technical Equipment Configuration (NTEC).

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Decompression Technique Diver

As you continue your technical diver training, one of the courses you’ll want to take is Decompression Techniques, in which you will gain a working knowledge of the theory, methods and procedures of planned stage decompression diving. Your training will include a minimum of six dives including planning and executing a standard stage decompression dive less than 130 fsw / 40 msw.

Your instructor will also teach you equipment requirements including team requirements and NAUI Technical Equipment Configuration (NTEC), and decompression breathing gas mixtures (including oxygen, Helitrox, and EANx). You’ll learn the practical skills and knowledge you need for decompression diving within course parameters.

If you are 18 years of age, posses at least NAUI Master Scuba Diver, Deep Diver Specialty, Technical EANx Diver and Helitrox Diver certifications (or their equivalents), and have 75 logged dives, you may enroll in the Decompression Techniques course. With additional dives and training, your instructor may opt to combine this course with

Technical EANx (Nitrox) Diver or Helitrox Diver.

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Heliair Diver

The NAUI Heliair Diver course provides the training and experience you need to competently plan and execute extended range dives that require stage decompression utilizing Heliair and EANx and/or oxygen. You’ll learn the hazards and proper use of Heliair for dives to maximum of 180 fsw / 55 msw that require stage decompression, utilizing EANx mixtures and/or oxygen during decompression.

This course may be combined with the Decompression Techniques Diver Course with additional dives and training. As with all courses, there are minimum requirements: for Heliair Diver, you must be 18 years of age; have logged at least 75 dives, (10 of which must be decompression dives in the environment in which the course is being taught); and be certified as a NAUI Technical EANx Diver, Decompression Techniques Diver unless combined with this course, and NAUI Helitrox Diver or equivalent thereof.

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Cavern Diver

Cavern Diver is a no-decompression course designed to teach you the fundamental skills and knowledge for cavern diving above 100 fsw / 30 msw and at a combined depth and distance penetration less than 200 feet / 60 meters from the surface.

During your course, you will complete a minimum of three cavern dives in at least two different sites within daylight and no-decompression limits, and become proficient in the use of spools and reels, team and line placement, and zero visibility/touch contact communications while following a line, as well as many other skills necessary to be a competent Cavern Diver.

Dive planning (including EANx if used) penetration distance within cavern diver limits, safety drills, equipment checks, gas sharing, guideline deployment and removal techniques, propulsion techniques, lost teammate and guideline drills and emergency procedures will also be covered in your Cavern Diver course.

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Cave Diver

Does the thought of diving through an underwater cave intrigue you? Are you fascinated by the possibility of diving where most divers never get to go? Cave Diver Levels I, II and III are actually three courses, each of which builds on skills and knowledge taught in the Cavern Diver course and/or respective previous level Cave Diver courses, giving you the next level of skills and experience you need to become a certified Level I, II or III Cave Diver.

Once you complete your Level I Cave Diver course, you will be able to plan and execute limited penetration, simple-navigation no decompression cave dives; certified Level II Cave Divers are qualified to plan and execute multiple navigational decisions on cave dives with staged cylinders; certified Level III Cave Divers are qualified to plan and execute extended penetration cave dives.

If you’re 18 years old and at least a NAUI Advanced Scuba Diver and Nitrox Diver with 75 logged dives, you may be ready for the challenge of cave diving!

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Ice Diver

NAUI’s Ice Diver course will provide you with a basic understanding of the knowledge and skills needed to minimize risks and gain experience in ice diving, penetration under solid ice.

During your Ice Diver course, you’ll master many skills and gain knowledge about ice dive organization, procedures, problems, risks and planning, equipment removal and replacement, underwater navigation, use of harnesses and line techniques, silt-out/black-water procedures, ice dive planning, exposure hazards and treatment, ice cutting and characteristics, signaling and much more.

You’ll also gain knowledge about atmospheric conditions and characteristics of ice structure; wind chill factors, cold stress, dehydration and first aid; surface clothing and dry suits; penetration holes and dive site preparation.

Your three required training dives will be limited to a maximum depth of 40 feet / 12 meters and not more than 100 feet /30 meters in a horizontal line from the penetration hole. You can enroll in the Ice Diver course as long as you are 18 years of age, have a NAUI Advanced Scuba Diver certification and have at least 50 logged dives in a variety of conditions.

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Wreck Diver (Penetration)

There are inherent hazards and risks associated with exploring an underwater wreck. The Wreck Penetration Diver course will give you the skills and knowledge you need to safely dive inside a sunken vessel, aircraft or similar structure.

You’ll learn about safety, hazards and special risks of overhead environments; gas management, entanglement, limited visibility, deep diving, equipment, sources of information, search methods, underwater navigation, legal aspects, artifacts, treasure, salvage, archaeology and appropriate material from other specialty courses as well.

If you have NAUI Advanced Scuba Diver and NAUI Wreck Diver (External Survey) certifications or the equivalent thereof and are at least 18, get ready to explore!

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Tri-Mix Diver

The Trimix Diver Course consists of two levels, Trimix Diver Level I and Trimix Diver Level II. These courses will give you the skills and knowledge needed to minimize the risks of utilizing helium-based Trimix breathing gas mixes for dives to a maximum depth of 250 fsw / 76 msw requiring stage decompression and utilizing EANx mixtures and/or oxygen during decompression.

Your Trimix Level I instructor will teach you to plan and execute technical dives that require stage decompression and utilize helium-based tri-mix breathing gas mixtures and EANx and/or oxygen for stage decompression to depths above 200 fsw / 61 msw. In your Tri-mix Level II course, you will learn how to safely extend your diving depths down to no greater than 250 fsw / 76 msw.

To enroll in either Trimix course, you must be certified as a NAUI Decompression Techniques Diver and Technical Helitrox Diver or equivalent, and have a minimum of 100 logged dives 20 of which must have been decompression dives.

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Closed Circuit Rebreather

The Closed Circuit Rebreather course provides the NAUI EANx certified diver with the training and experience necessary to understand the hazards and minimize the risks of using a closed circuit rebreather while breathing Nitrox with a constant oxygen partial pressure.

This no-stop decompression course is designed to provide you with the skills and knowledge needed to minimize the risks of using Closed-circuit Underwater Breathing

Apparatus to a maximum depth of 100 fsw / 30 msw.

Closed-circuit Underwater Breathing Apparatus used for NAUI certification and training must have been independently tested for authorization of training on a specific model.

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Intro To Tech

The Introduction to Technical Diving Course (Intro to Tech) is designed as a bridge from the recreational diver to an introduction to the rigors and discipline of technical diving, and is a great preparatory course if you are considering technical diver training or interested in streamlining your equipment configuration.

Your NAUI Intro to Tech instructor will introduce you to dive planning, physics and physiology, decompression, and decompression associated with technical diving. The NAUI Technical Equipment Configuration (NTEC) course may also be available as part of your Intro to Tech course or as a separate technical course.

The Intro to Tech course is your first step to a whole new world of technical diving!

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Closed Circuit Mixed Gas Diver

NAUI’s Closed Circuit Mixed Gas Diver course will to provide you with the skills and knowledge needed to minimize the risks of utilizing helium-based or trimix breathing diluent gas mixes for diving, with dive parameters to a maximum depth of 250 fsw / 76 msw requiring decompression with rebreathers and constant PO2.

Your training will include dive planning limits based on gas consumption of bailout stages, oxygen exposures, inert gas loading and breathing gas mixtures; navigation, diver rescue and management of a diver experiencing oxygen toxicity; ascents with ascent reel and lift bag; and stage decompression.

The Closed Circuit Mixed Gas Diver course is an intensive class that requires previous certifications in NAUI Decompression Techniques, Heliair, and Closed Circuit Rebreather (CCR) or the equivalents thereof, plus a minimum of 100 logged hours on a Closed Circuit Rebreather, 60 hours of which are directly on the specific CCR for mixed gas training.

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Mixed Gas Blender and Oxygen Service Technician

If you want to prepare EANx breathing gas mixtures for use by divers, sign up for the Mixed Gas Blender and Oxygen Service Technician course. This is a great course if you plan to work in a dive center and need additional training, or wish to expand your knowledge of diving gas mixtures.

In it, you’ll gain the skills and knowledge needed to safely handle high pressure gases and prepare Nitrox breathing gas mixtures for use by divers. You’ll analyze the resulting breathing gas mixtures from your own breathing gas blending practice and master the breathing gas blending system used in training.

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Semi-closed Circuit Rebreather Diver

The Semi-closed Circuit Rebreather Diver course will provide you with the skills and knowledge you need to minimize the risks of using Semi-closed Circuit Rebreathers (SCR) to a maximum depth of 100 fsw / 30 msw and while using Nitrox mixtures of 32% to 80% oxygen.

Your training will include analyzation of breathing gas mixtures; buoyancy control skills; scuba diver rescue simulation to including management of a diver experiencing underwater convulsions, hypoxia, flooded system, and out of breathing gas scenarios; training in redundant breathing gas systems; proper counter lung flush procedures; and ascent with a line reel and lift bag while simulating a required decompression stop. Additional topics covered in your course include proper post dive procedures, physics and physiology, equipment; review of dive tables including RGBM tables, narcosis depth, dive planning requirements and gas management planning.

Semi-closed Circuit Rebreathers used for NAUI certification courses must have been independently tested before training on a specific model can be authorized.

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Technical Wreck Penetration Diver

Combine technical diving and wreck exploration and you get Technical Wreck Penetration diving…This course is to provide the diver with the skills and knowledge needed to gain experience and minimize risks in penetration wreck diving at depths beyond 130 fsw / 40 msw.

In this intensive and interesting course you’ll learn to plan and execute penetration wreck dives that require stage decompression and utilize air and EANx and/or oxygen for stage decompression, with dive plans less than 165 fsw / 50 msw.

To enroll in the Technical Wreck Penetration Diver course, you must be at least 18, have a minimum certification as a Penetration Wreck Diver with at least 10 logged penetration wreck dives, minimum 50 logged dives total, and certification in Technical NAUI EANx and Decompression Techniques. Your NAUI instructor may combine this course with your Decompression Techniques Course.

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Approved Rebreathers

CCR 1000 MK 15 SM 1600 SM 15.5 MK 16 DRAEGER DOLPHIN DRAEGER RAY PRISM TOPAZ OXILUNG (MILITARY) LAR V (MILITARY) VOYAGER CCR AND SCR The Evolution The Inspiration

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