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Nitrox. Nitrox is known by many names: Enhanced Air Nitrox, Oxygen Enriched Air
Nitrox, Nitrox, EANx or Safe Air. The PADI Enriched Air Nitrox Specialty Course teaches
certified divers to use air with added oxygen, up to 40%.
Diving with this special mix allows for longer bottom times
and safer diving. The course consists of academic learning,
dive planning, and two open water dives, which can be done
from our regularly scheduled dive trips. Divers learn
to analyze the oxygen percentage in the tank before each dive.
Completing the course is easy and doesn't take much time!
Once you learn about Nitrox, you'll see why it is so much safer
and everyone is using it. The course has a book, 2 tables
(formatted after the Open Water tables) and a 45 minute video
that takes you through the course step by step. The class time
is about 5 hours. You will go over the material you have read
and watched in the video, take an exam and Ta Dan, you are
ready to dive! All you need is a 2 tank dive on Nitrox and
you are certified! It's that easy!!!!
The course prerequisite is 15 years old and Open Water Diver.
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Nitrox refers to any gas mixture composed
(excluding trace gases) of nitrogen and oxygen; this includes
normal air which is approximately 78% nitrogen and 21% oxygen,
with around 1% other gases. The most common use of Nitrox mixtures
containing higher than normal levels of oxygen is in SCUBA diving
where the reduced percentage of nitrogen is advantageous in
reducing nitrogen take up in the body's tissues and so extending
the possible dive time and/or reducing the risk of decompression
sickness (also known as the bends).
Nitrox is mainly used in scuba diving to reduce the
proportion of nitrogen in the breathing gas mixture.
Reducing the proportion of nitrogen by |
| increasing the proportion of oxygen reduces the risk of
decompression sickness, allowing extended dive times without
increasing the need for decompression stops. Nitrox is not a
safer gas than compressed air in all respects: although its
use reduces the risk of decompression sickness, it increases
the risk of oxygen toxicity and fire, which are further
discussed below. |
| It is generally untrue that breathing
Nitrox can reduce the effects of nitrogen narcosis, as oxygen
seems to have equally narcotic properties under pressure;
thus one should not expect a reduction in narcotic effects
due only to the use of Nitrox. For a reduction in narcotic
effects Trimix gases which also contain helium are generally
used. There is anecdotal evidence that the use of
Nitrox reduces post-dive fatigue, particularly in older and
or obese divers; however the only known double-blind study
to test this found no |
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| statistically significant reduction in reported fatigue.
There has, however, been some suggestion that post dive
fatigue is due to sub-clinical decompression sickness (DCS)
(i.e. micro bubbles in the blood insufficient to cause
symptoms of DCS); the fact that the study mentioned was
conducted in a dry chamber with an ideal decompression
profile may have been sufficient to reduce sub-clinical DCS
and prevent fatigue in both Nitrox and air divers. |
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Further studies with a number of different
dive profiles, and also different levels of exertion, would
be necessary to fully investigate this issue. For example,
there is much better scientific evidence that breathing
high-oxygen gases increase exercise tolerance, during
aerobic exertion. Though even moderate exertion while
breathing from the regulator is a relatively uncommon
occurrence in scuba, as divers usually try to minimize it in
order to conserve gas, episodes of exertion while
regulator-breathing do occasionally occur in sport diving.
Examples are surface-swimming a distance to a boat or beach
after surfacing, where residual "safety"
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| cylinder gas is often used freely, since the remainder
will be wasted anyway when the dive is completed. It is
possible that these so-far un-studied situations have
contributed to some of the positive reputation of Nitrox. |
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History.
In 1959 the United States Navy (USN) documented enriched
oxygen gas procedures for the military use of what we
today call Nitrox, in the USN Diving Manual.
Ving Center, began instituting diving procedures for
oxygen-enriched air. He also developed a process for mixing
oxygen and air which he called a continuous blending system.
For many years Dr. Wells' invention was the only practical
alternative to partial pressure blending. In 1979 NOAA
published Wells' procedures for the scientific use
of Nitrox in the NOAA Diving Manual.
In 1985 Dick Rutkowski, a former NOAA diving safety
officer, formed IAND (International Association of Nitrox Divers)
and began teaching Nitrox use for recreational diving. This
was considered heresy by some, and met with heavy skepticism
by the diving community. In 1992 the name was changed to the
International Association of Nitrox and Technical Divers
(IANTD), the T being added when the European Association
of Technical Divers (EATD) merged with IAND. In the early
1990s, the agencies teaching Nitrox were not the main
scuba agencies. New organizations, including Ed Betts'
ANDI (American Nitrox Divers International), which invented
the term "Safe Air" for marketing purposes, and Bret
Gilliam's TDI (Technical Divers International) gave
scientific credence to Nitrox.
Meanwhile, diving stores were finding a purely economic
reason to offer Nitrox: not only was an entire new course
and certification needed to use it, but instead of cheap or free
tank fills with compressed air, dive shops found they could
charge premium amounts of money for custom-gas blending of
Nitrox to their ordinary moderately experienced divers.
With the new dive computers which could be programmed to
allow for the longer bottom-times and shorter residual
nitrogen times which Nitrox gave.
In 1970, Dr. Morgan Wells, who was the first director
of the National Oceanographic and Atmospheric Administration
(NOAA) Di, the incentive for the sport diver to use the gas
increased. An intersection of economics and scientific
validity had occurred. However, in the meantime during the
early 90's, a number of feelings were hurt.
In 1996, the Professional Association of Diving Instructors
(PADI) announced full educational support for Nitrox.
While other main line scuba organizations had announced
their support of Nitrox earlier, it was PADI's endorsement
that put Nitrox over the top as a standard
sport diving "option". |
Contact Information.
Neptune Dive Center. 312/12 Pattaya 3rd Road, Pattaya, 20150, Chonburi, Thailand.
Tel: 038-720603 Fax: 038-720608
Mobile: English, Nederlands, Deutsch.
086-1532636
Mobile: Thai 081-1509562
Email:
scuba@tttmaxnet.com
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