Did you know that Enriched Air Nitrox is the most popular of the PADI Specialty Courses, and one of the best choices for additional diver training? So what’s it all about and how do you become a certified nitrox diver?
Stay down longer and get back in the water sooner
Nitrox is a term for any mixture of Nitrogen and Oxygen, and Enriched Air Nitrox is air that has been “enriched” to contain more than the 21% Oxygen we breathe on land, or is in a normal scuba cylinder. In an EAN (Enriched Air Nitrox) blend the oxygen content can range from 21-40% Oxygen (for recreational no-decompression diving) but the most common blends are 32% and 36% Oxygen.Tanks filled with EAN are clearly marked with a distinctive green and yellow nitrox band so as not to be confused with normal air tanks.
When we dive, the water pressure causes nitrogen in the air we are breathing to dissolve into our bloodstream. The higher the pressure (the deeper we dive) the more nitrogen will dissolve. It is the amount of nitrogen that we absorb whilst diving that can lead to an increased chance of decompression illness, and that dictates our no decompression limits (the maximum amount of time we can spend at a specific depth).
Nitrox allows increased dive time at specific depths
The biggest benefit of diving with enriched air Nitrox is that as the amount of oxygen in a mix increases, the amount of nitrogen decreases and the less nitrogen there is in a diver’s breathing gas, the slower the nitrogen absorption will be at a given depth allowing us to extend no-decompression limits.
Enriched air does not allow us to dive deeper – but, within the recreational 18 – 30 m range, it significantly extends no stop time or time at specific depths, and can considerably increase available dive time. For instance, if we compare the NoD (No decompression limits) from the air and nitrox RDP’s (Recreational Dive Planners or tables) at 18 and 22 metres:
Shorter Surface Intervals
It therefore follows that a nitrox diver does not have as much nitrogen to “off-gas” during a surface interval, which can shorten the required surface interval significantly.
Longer Repetitive Dive Times
Nitrox becomes especially useful for divers who complete more than one dive per a day and is most commonly used on liveaboard adventures where it is common to do multiple dives per day.
A diver using Nitrox will have a longer allowable bottom time on a repetitive dive than a diver using air because the diver using nitrox has previously absorbed less nitrogen.
Many nitrox divers- especially those with certain risk factors for decompression sickness, such as previous DCS hits, physical injuries or older age-choose to use nitrox while following air tables to add a significant buffer zone to their no-decompression limits.
There is a significant amount of anecdotal evidence that using Nitrox may reduce post dive fatigue significantly
Nitrox is especially beneficial for:
- Deeper sites such as Kled Gaeow Wreck, the King Cruiser Wreck, Hin Daeng & Hin Muang (sites where your dive time is determined more by your NDL than your air supply)
- Older divers or divers with certain health concerns
- Multiple day Diving – repetitive dives over multiple days, especially liveaboards
What does the Nitrox Course involve?
The PADI Enriched Air Diver Course can be taught as a 1 day stand alone Specialty Course, an add on to your day’s fun diving, or an upgrade to your Advanced Course and is open to anyone with Open Water certification or above (aged 12 years or more).
There is a short video, a knowledge review and short quiz to complete, explaining a little more about how the higher oxygen content poses some easily managed risks related to oxygen exposure and toxicity.
Your instructor will teach you to analyze the oxygen content of your tank before use, as well as how to determine the maximum operating depth for that blend which you record on an EAN Fill Log for each tank.
The course can be taught as a dry course since there are no underwater skills or dives required for certification, or you have the option to complete 2 dives on nitrox.
- PADI Enriched Air Nitrox Specialty including 2 dives – 7,900 THB
- PADI Enriched Air Nitrox Specialty (Dry course) – 5,400 THB
- Add on to a day’s Fun Diving – 5,400 THB
- Add on/Upgrade from Advanced Course (1 extra dive) – 6,600 THB
- Add on/Upgrade from Advanced Course (no additional dives) – 5,400 THB