The PADI Enriched Air Course  [FREQUENTLY ASKED QUESTIONS]

Nitrox is any combination of Oxygen and Nitrogen as an underwater breathing medium. "Enriched Air Nitrox" or EANx for short, is a combination where the percentage of Oxygen is higher than the 21% found in 'normal' air, hence allowing divers to lower the partial pressure of nitrogen in their breathing gas.

This lets divers to breathe comparatively less nitrogen on all dives, increasing their bottom time and/or increasing their safety limits when compared to air diving. It is not a "Devil Gas" but a breathing mix of contemporary and future diving. One agency refers to it as "Safe Air" while others regard it simply as Nitrox. 

Can Nitrox be used at depth?

The lower partial pressure of Nitrogen in the breathing mix is the trick. The difference in bottom times in the 18-26 metre range when compared to air diving is notable, increasing the no-decompression limits by about twice or over. But, the deeper a diver goes, the less significant this difference becomes. Nitrox can be used to a depth where the partial pressure of Oxygen is within safe limits (1.4 according to PADI) but divers should still take into account the potential for nitrogen narcosis. Although divers dive to a certain depth, the lowered rate of Nitrogen makes the body perceive this as being a shallower depth when compared to diving air.

How does Nitrox Work?

The most common EANx mixtures throughout the world are 32 and 36 percent, meaning 32 or 36 percent Oxygen in the mix. In normal air, there is 21% Oxygen and 79% Nitrogen (ignoring the 'trace' gases). In a 32% mix, the amount of nitrogen is down to 68% whereas in a 36% mix, it is further lowered to 64%. Lowering the Nitrogen content makes our body intake less Nitrogen at given depths. Our body 'feels' it is at a shallower depth and the no-decompression limits for that shallower depth are used to set the bottom time. If a diver was doing an "air" dive to 24 metres, his/her RDP depth would be set for 24 metres. Using Nitrox 36 to this depth though, the diver can run a dive according to its "Equivalent Air Depth" of 17.5 or 18 metres. Hence the extra bottom time.

Who can dive Nitrox?

According to the standards, any diver from Open Water Diver upwards may take the PADI Enriched Air Nitrox Diver speciality course. Only certified Nitrox divers may purchase nitrox from dive centres.

Do I need special equipment?

No, not really. Basic nitrox courses offered by various agencies such as PADI, BSAC, TDI and IANTD allow divers to use a 'bottom gas' ranging from 22 to 40 percent Oxygen at maximum. Unless otherwise specified by the manufacturer, using up to 40% O2 in the breathing medium in Britain does not require special equipment. Generally speaking normal air regulators and pressure gauges can be used without modification unless the manufacturer . This is because regulators, BCDs, LPIs and SPGs never come in contact with high levels of "pure" Oxygen. Note than this standard may vary from country to country and could change for the United Kingdom in the future.

Do I need "Oxygen Serviced" cylinders?

Yes, in the United Kingdom you do. General practice in British diving operations is to "partial pressure blend" your mix. In other words, unlike in some American states, we do not use "premixes." Dive centres have to prepare tailor-made mixes for divers which involves filling the tanks first with 100% Oxygen to a calculated limit and then "top it off" with air to get the right mix. At this stage your cylinder and valve come in contact with 100% Oxygen. Oxygen, in contact with hydrocarbons such as silicone grease, could lead to problems. Because of this your cylinder, valve, o-rings and other components will be cleaned of any 'contamination' while all oils are replaced with O2 friendly greases. From then onwards, you will need to make sure your bottle is "Oxygen Serviced" every year. 

 Which course should I take?

 This pack consists of your own user-friendly manual, two separate nitrox RDPs for 32 and 36 percent mixes (which are interchangeable between themselves and your blue air RDP!), a waterproof slate which has all useful EADs and CNS exposure limits.

The second day of the course is devoted to using nitrox in the water. PADI does not require any inwater skills on the two nitrox dives you conduct as the 'skill' requirement is to be able to choose and use your own mix after analysing it. This is a great advantage as you can combine these nitrox dives with any PADI speciality and conduct the dives of that speciality using nitrox. This is the only course where PADI allows combined dives to take place so if you were ever interested to do more, i.e. learn and conduct a drift dive and become a speciality diver in that field or try the PADI wreck, deep or other specialities, this is the best option.

What does the course price include?

The course price includes the student crew-pak (manual & three slates), training and certification fees. Gases (chosen by you after the academic training) and boat costs are not included and have to be paid to relevant operators chosen by our Centre. It is a comprehensive package offered only by our Centre because our staff, all active gas divers, believe the use of Nitrox should be wide spread. Please Note: All students at Underwater Explorers have 10% off any safety equipment purchases throughout the duration of their course.