Trimix
Encyclopedia
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.
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.
The mixture of helium and oxygen with a 0% nitrogen content is generally known as Heliox
. This is frequently used as a breathing gas in deep commercial diving operations, where it is often recycled to save the expensive helium component. Analysis of two-component gases is much simpler than three component gases.
and other physiological effects of the gas at depth. Helium has very little narcotic effect.
A lower proportion of oxygen reduces the risk of oxygen toxicity
on deep dives.
The lower density of helium reduces breathing resistance at depth.
Because of its low molecular weight, helium enters and leaves tissues more rapidly
than nitrogen as the pressure is increased or reduced (this is called on-gassing and off-gassing). Because of its lower solubility, helium does not load tissues as heavily as nitrogen, but at the same time the tissues can not support as high an amount of helium when super-saturated. In effect, helium is a faster gas to saturate and desaturate, which is a distinct advantage in saturation diving, but less so in bounce diving, where the increased rate of off-gassing is largely counterbalanced by the equivalently increased rate of on-gassing.
, 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. Dry suits (if used together with a buoyancy compensator) 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.
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, and helium is more likely to come out of solution and cause decompression sickness
following a fast ascent.
and duration of the dive before which oxygen toxicity becomes a limiting factor. Most trimix divers limit their working oxygen partial pressure [PO2] to 1.4 and may reduce the PO2 further to 1.3 or 1.2 depending on the depth, the duration and the kind of breathing system used [open circuit vs closed circuit rebreather].
, a problem that can occur when breathing heliox
at depths beyond about 130 metres (426.5 ft). Nitrogen is also much less expensive than helium.
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 to 1.6 bar and maximum equivalent narcotic depth of 30 to 50 m (98.4 to 164 ft). At 100 m (328.1 ft), "12/52" has a PPO2 of 1.3 bar and an equivalent narcotic depth of 43 m (141.1 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. A normoxic mix such as "19/30" is used in the 30 to 60 m (98.4 to 196.9 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 rebreather
s that use trimix diluents, the mix can be hyperoxic in shallow water because the rebreather automatically adds oxygen to maintain a specific ppO2. 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.
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.
A second method called 'continuous blending' is now gaining favor. 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 mixture 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 of a sample flow and the trimix is analyzed (preferably for both 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. This is important mainly because of the high cost of helium.
Drawbacks may be that the high heat of compression of helium results in the compressor overheating (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).
(END) of the mix at approximately 34 metres (111.5 ft), 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. 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.
The method of mixing a known nitrox mix with helium allows analysis of the fractions of each gas using only an oxygen analyser, since the ratio of the oxygen fraction in the final mix to the oxygen fraction in the initial nitrox gives the fraction of nitrox in the final mix, hence the fractions of the three components are easily calculated. It is demonstrably true that the END of a nitrox-helium mixture at its maximum operating depth
(MOD) is equal to the MOD of the nitrox alone.
(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 (144.4 ft), where it has an equivalent narcotic depth
of 35 metres (114.8 ft). This allows diving throughout the usual recreational range, while decreasing decompression obligation and narcotic effects compared to air.
GUE
and UTD
also promote hyperoxic trimix, but prefer the term "TriOx".
Other divers question whether this proliferation of terminology is useful, and feel that the term Trimix is sufficient, modified as appropriate with the terms hypoxic, normoxic and hyperoxic, and the usual forms for indicating constituent gas fraction.
in 1939. Heliox
was used with air tables resulting in a high incidence of decompression sickness so the use of helium was discontinued.
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 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.
1979: A research team headed by Peter B. Bennett
at the Duke University Medical Center Hyperbaric Laboratory began the "Atlantis Dive Series" which proved the mechanisms behind the use of trimix to prevent High Pressure Nervous Syndrome symptoms.
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.
1995: The National Oceanographic and Atmospheric Administration (NOAA) and Key West Divers team up to conduct the first NOAA-sponsored trimix dives on the wreck of USS Monitor off Cape Hatteras, NC. NOAA's mix, initially called "Monitor Mix" became NOAA Trimix I, with decompression tables published in the NOAA Diving Manual.
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
, dying while repeating the dive.
Source:
Breathing gas
Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...
, consisting of oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
, helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
and nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, and is often used in deep commercial diving
Commercial Diving
Professional diving is a type of diving where the divers are paid for their work. There are several branches of professional diving, the most well known of which is probably commercial diving...
and during the deep phase of dives carried out using technical diving
Technical diving
Technical diving is a form of scuba diving that exceeds the scope of recreational diving...
techniques.
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.
The mixture of helium and oxygen with a 0% nitrogen content is generally known as Heliox
Heliox
Heliox is a breathing gas composed of a mixture of helium and oxygen .Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of...
. This is frequently used as a breathing gas in deep commercial diving operations, where it is often recycled to save the expensive helium component. Analysis of two-component gases is much simpler than three component gases.
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. A lower proportion of nitrogen is required to reduce nitrogen narcosisNitrogen narcosis
Narcosis while diving , is a reversible alteration in consciousness that occurs while scuba diving at depth. The Greek word ναρκωσις is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates...
and other physiological effects of the gas at depth. Helium has very little narcotic effect.
A lower proportion of oxygen reduces the risk of oxygen toxicity
Oxygen toxicity
Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen at elevated partial pressures. It is also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning...
on deep dives.
The lower density of helium reduces breathing resistance at depth.
Because of its low molecular weight, helium enters and leaves tissues more rapidly
Graham's law
Graham's law, known as Graham's law of effusion, was formulated by Scottish physical chemist Thomas Graham in 1846. Graham found experimentally that the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles...
than nitrogen as the pressure is increased or reduced (this is called on-gassing and off-gassing). Because of its lower solubility, helium does not load tissues as heavily as nitrogen, but at the same time the tissues can not support as high an amount of helium when super-saturated. In effect, helium is a faster gas to saturate and desaturate, which is a distinct advantage in saturation diving, but less so in bounce diving, where the increased rate of off-gassing is largely counterbalanced by the equivalently increased rate of on-gassing.
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. ArgonArgon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
, 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. Dry suits (if used together with a buoyancy compensator) 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
Arthralgia
Arthralgia literally means joint pain; it is a symptom of injury, infection, illnesses or an allergic reaction to medication....
during descent.
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, and helium is more likely to come out of solution and cause decompression sickness
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
following a fast ascent.
Advantages of reducing oxygen in the mix
Lowering the oxygen content increases the maximum operating depthMaximum operating depth
In technical diving and nitrox diving, the maximum operating depth of a breathing gas is the depth at which the partial pressure of oxygen of the gas mix exceeds a safe limit...
and duration of the dive before which oxygen toxicity becomes a limiting factor. Most trimix divers limit their working oxygen partial pressure [PO2] to 1.4 and may reduce the PO2 further to 1.3 or 1.2 depending on the depth, the duration and the kind of breathing system used [open circuit vs closed circuit rebreather].
Advantages of keeping some nitrogen in the mix
Retaining nitrogen in trimix can contribute to the prevention of High Pressure Nervous SyndromeHigh pressure nervous syndrome
High-pressure nervous syndrome is a neurological and physiological diving disorder that results when a commercial diver or scuba diver descends below about while breathing a helium–oxygen mixture. The effects depend on the rate of descent and the depth...
, a problem that can occur when breathing heliox
Heliox
Heliox is a breathing gas composed of a mixture of helium and oxygen .Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of...
at depths beyond about 130 metres (426.5 ft). Nitrogen is also much less expensive than helium.
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" or trimix 10/70/20, consisting of 10% oxygen, 70% helium, 20% nitrogen is suitable for a 100 metres (328.1 ft) dive.The ratio of gases in a particular mix is chosen to give a safe maximum operating depth
Maximum operating depth
In technical diving and nitrox diving, the maximum operating depth of a breathing gas is the depth at which the partial pressure of oxygen of the gas mix exceeds a safe limit...
and comfortable equivalent narcotic depth
Equivalent narcotic depth
Equivalent narcotic depth is used in technical diving as a way of estimating the narcotic effect of a breathing gas mixture, such as heliox and trimix...
for the planned dive. Safe limits for mix of gases in trimix are generally accepted to be a maximum partial pressure
Partial pressure
In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
of oxygen (ppO2—see Dalton's law
Dalton's law
In chemistry and physics, Dalton's law states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture...
) of 1.0 to 1.6 bar and maximum equivalent narcotic depth of 30 to 50 m (98.4 to 164 ft). At 100 m (328.1 ft), "12/52" has a PPO2 of 1.3 bar and an equivalent narcotic depth of 43 m (141.1 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. A normoxic mix such as "19/30" is used in the 30 to 60 m (98.4 to 196.9 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 rebreather
Rebreather
A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...
s that use trimix diluents, the mix can be hyperoxic in shallow water because the rebreather automatically adds oxygen to maintain a specific ppO2. Less commonly, hyperoxic trimix is sometimes used on open circuit scuba. Hyperoxic trimix is sometimes referred to as Helitrox or TriOx.
See breathing gas
Breathing gas
Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...
for more information on the composition and choice of gas blends.
Blending
Gas blendingGas blending
Gas blending or gas mixing is the filling of diving cylinders with non-air breathing gases such as nitrox, trimix and heliox.Filling cylinders with a mixture of gases has dangers for both the filler and the diver. During filling there is a risk of fire due to use of oxygen and a risk of explosion...
of trimix involves decanting
Decantation
Decantation is a process for the separation of mixtures. This is achieved by carefully pouring a solution from a container in order to leave the precipitate in the bottom of the original container...
oxygen and helium into the diving cylinder
Diving cylinder
A diving cylinder, scuba tank or diving tank is a gas cylinder used to store and transport high pressure breathing gas as a component of a scuba set. It provides gas to the scuba diver through the demand valve of a diving regulator....
and then topping up the mix with air from a diving air compressor
Diving air compressor
A Diving Air Compressor is a gas compressor that can provide breathing air directly to a surface-supplied diver, or fill diving cylinders with high-pressure air pure enough to be used as a breathing gas.thumb|right|Filling a cylinder from the panel...
. 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
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
is achieved. This process often takes hours and is sometimes spread over days at busy blending stations.
A second method called 'continuous blending' is now gaining favor. 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 mixture 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 of a sample flow and the trimix is analyzed (preferably for both 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. This is important mainly because of the high cost of helium.
Drawbacks may be that the high heat of compression of helium results in the compressor overheating (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).
"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 depthEquivalent narcotic depth
Equivalent narcotic depth is used in technical diving as a way of estimating the narcotic effect of a breathing gas mixture, such as heliox and trimix...
(END) of the mix at approximately 34 metres (111.5 ft), 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. 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.
The method of mixing a known nitrox mix with helium allows analysis of the fractions of each gas using only an oxygen analyser, since the ratio of the oxygen fraction in the final mix to the oxygen fraction in the initial nitrox gives the fraction of nitrox in the final mix, hence the fractions of the three components are easily calculated. It is demonstrably true that the END of a nitrox-helium mixture at its maximum operating depth
Maximum operating depth
In technical diving and nitrox diving, the maximum operating depth of a breathing gas is the depth at which the partial pressure of oxygen of the gas mix exceeds a safe limit...
(MOD) is equal to the MOD of the nitrox alone.
Hyperoxic trimix
The National Association of Underwater InstructorsNational Association of Underwater Instructors
The National Association of Underwater Instructors is a non-profit 501 association of SCUBA instructors. It was officially CE and ISO certified in May 2007 in all three diver levels and both instructor levels.-History:...
(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
Maximum operating depth
In technical diving and nitrox diving, the maximum operating depth of a breathing gas is the depth at which the partial pressure of oxygen of the gas mix exceeds a safe limit...
of 44 metres (144.4 ft), where it has an equivalent narcotic depth
Equivalent narcotic depth
Equivalent narcotic depth is used in technical diving as a way of estimating the narcotic effect of a breathing gas mixture, such as heliox and trimix...
of 35 metres (114.8 ft). This allows diving throughout the usual recreational range, while decreasing decompression obligation and narcotic effects compared to air.
GUE
Global Underwater Explorers
Global Underwater Explorers is a scuba diving organization that provides education within recreational, technical and cave diving. It is a not-for-profit, membership organization, based in High Springs, Florida, United States....
and UTD
Unified Team Diving
Unified Team Diving is a SCUBA diving training agency founded in 2008 to incorporate DIR/Hogarthian principles into SCUBA education at all levels.-History:...
also promote hyperoxic trimix, but prefer the term "TriOx".
Other divers question whether this proliferation of terminology is useful, and feel that the term Trimix is sufficient, modified as appropriate with the terms hypoxic, normoxic and hyperoxic, and the usual forms for indicating constituent gas fraction.
History 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. The effects from narcosis was not proven until the salvage of the USS SqualusUSS Sailfish (SS-192)
USS Sailfish , a , was originally named Squalus.Her keel was laid on 18 October 1937 by the Portsmouth Naval Shipyard in Kittery, Maine, as Squalus, the only ship of the United States Navy named for the squalus. She was launched on 14 September 1938 sponsored by Mrs. Thomas C...
in 1939. Heliox
Heliox
Heliox is a breathing gas composed of a mixture of helium and oxygen .Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of...
was used with air tables resulting in a high incidence of decompression sickness so the use of helium was discontinued.
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 Max "Gene" Nohl's dive to 127 meters.
1939: US Navy used heliox in USS Squalus
USS Sailfish (SS-192)
USS Sailfish , a , was originally named Squalus.Her keel was laid on 18 October 1937 by the Portsmouth Naval Shipyard in Kittery, Maine, as Squalus, the only ship of the United States Navy named for the squalus. She was launched on 14 September 1938 sponsored by Mrs. Thomas C...
salvage operation.
1965: First saturation dives using heliox.
1970: Hal Watts performs dual body recovery at Mystery Sink (126 m). Cave divers
Cave diving
Cave diving is a type of technical diving in which specialized equipment is used to enable the exploration of caves which are at least partially filled with water. In the United Kingdom it is an extension of the more common sport of caving, and in the United States an extension of the more common...
Sheck Exley
Sheck Exley
-Biography:Exley is widely regarded as one of the pioneers of cave diving, writing two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man published by Cave Books, , and establishing many of the basic safety procedures used in cave and overhead...
and Jochen Hasenmayer use heliox to a depth of 212 meters.
1979: A research team headed by Peter B. Bennett
Peter B. Bennett
Peter B. Bennett is the founder and former president and CEO of the Divers Alert Network , a non-profit organization devoted to assisting scuba divers in need. He is a professor of anesthesiology at Duke University Medical Center, and is currently the Senior Director of the Center for Hyperbaric...
at the Duke University Medical Center Hyperbaric Laboratory began the "Atlantis Dive Series" which proved the mechanisms behind the use of trimix to prevent High Pressure Nervous Syndrome symptoms.
1987: First mass use of trimix and heliox: Wakulla Springs
Wakulla Springs
Wakulla Springs is located south of Tallahassee, Florida and east of Crawfordville in Wakulla County, Florida at the crossroads of State Road 61 and State Road 267...
Project. Exley teaches non-commercial divers in relation to trimix usage in cave diving.
1991: Billy Deans
Billy Deans (diver)
"Captain" Billy Deans is a pioneering wreck and technical diver. Although "Captain" is the nickname which is universally applied to Billy Deans, he is in fact a US Coast Guard rated captain up to 100 tons....
commences teaching of trimix diving for recreational diving. Tom Mount
Tom Mount
Tom Mount is a pioneering technical diver. In 1991 Tom Mount joined Dick Rutkowski in the new organisation formed by Rutkowski, IANTD, dedicated to teaching Nitrox to recreational divers. In 1992 Tom was named President and Chief Executive Office of IANTD, a position that he held until 2005...
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
John Chatterton
John Chatterton is one of the world’s most accomplished and well known wreck divers. Together with Richie Kohler, he was one of the co-hosts for the History Channel’s Deep Sea Detectives where they have completed work on 57 episodes of this successful series...
and Gary Gentile
Gary Gentile
Gary Gentile is an American author and pioneering technical diver.-Diving:Gary Gentile is a wreck diver. It has been suggested that Gary Gentile may be the most experienced wreck diver in the world...
, successfully complete a series of wreck dives
Wreck diving
Wreck diving is a type of recreational diving where shipwrecks are explored. Although most wreck dive sites are at shipwrecks, there is an increasing trend to scuttle retired ships to create artificial reef sites...
on the RMS Lusitania
RMS Lusitania
RMS Lusitania was a British ocean liner designed by Leonard Peskett and built by John Brown and Company of Clydebank, Scotland. The ship entered passenger service with the Cunard Line on 26 August 1907 and continued on the line's heavily-traveled passenger service between Liverpool, England and New...
expedition to a depth of 100 meters using trimix.
1995: The National Oceanographic and Atmospheric Administration (NOAA) and Key West Divers team up to conduct the first NOAA-sponsored trimix dives on the wreck of USS Monitor off Cape Hatteras, NC. NOAA's mix, initially called "Monitor Mix" became NOAA Trimix I, with decompression tables published in the NOAA Diving Manual.
2001: The Guinness Book of records recognises John Bennett
John Bennett (diver)
John Bennett was a British SCUBA diver who is best known for setting a world record by becoming the first person to deep dive below a depth of 1,000 feet on self contained breathing apparatus on 6 November 2001....
as the first scuba diver to dive to 1000 ft, using Trimix.
2005: David Shaw
David Shaw (diver)
David Shaw was an Australian scuba diver, a technical diver and an airline pilot for Cathay Pacific, who flew the A330-300, A340-300 and A340-600...
sets depth record for using a trimix rebreather
Rebreather
A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...
, dying while repeating the dive.
Source:
See also
- Argox
- HelioxHelioxHeliox is a breathing gas composed of a mixture of helium and oxygen .Heliox has been used medically since the 1930s, and although the medical community adopted it initially to alleviate symptoms of upper airway obstruction, its range of medical uses has since expanded greatly, mostly because of...
- HydrelioxHydrelioxHydreliox is an exotic breathing gas mixture of helium, oxygen and hydrogen.It is used primarily for research and scientific deep diving, usually below . Below this depth, extended breathing of heliox gas mixtures may cause high pressure nervous syndrome . Two gas mixtures exist that attempt to...
- HydroxHydrox (breathing gas)Hydrox, a gas mixture of hydrogen and oxygen, is used as a breathing gas in very deep diving. It allows divers to descend several hundred metres....
- Nitrox