Nitrox (EAN - Enriched Air Nitrox)

This is air enriched with oxygen. Since nitrogen (a component of air) is a gas that limits our no-decompression time underwater - a smaller amount of it in the breathing gas will extend the no-decompression limit. If we replace a part of nitrogen with oxygen - we will get nitrox. The less nitrogen in the mix and the more oxygen - the longer our no-decompression limit will be. It may seem that this is a perfect solution. And this is the case if the diver knows (and this is learned during the Enriched Air Nitrox Diver specialization course - EAN Diver), that oxygen at partial pressure greater than 1.4 ata (emergency 1.6 ata) is toxic to the central nervous system. This means that increasing the amount of oxygen in the gas mixture extends our no-decompression limit and at the same time decreases the maximum diving depth. And reduces it depending on the oxygen content in the mixture - the more oxygen, the longer the no-decompression limit of the dive and the shallower the depth compared to diving on air.

Therefore, if you want to dive on nitrox, you must complete the EAN - Enriched Air Diver course and always independently check the composition of the breathing mixture - using an oxygen analyzer.

The undisputed advantages of diving with nitrox are:

• Extending the no-decompression limits (compared to the limits during air dives)
• Shortening the surface intervals – important during a series of dives in one day (for example, during a diving safari)

At our diving center in Hurghada, an oxygen analyzer is always available on the boat.

Recreational divers can use nitrox with a maximum percentage of oxygen of 40%. Standard nitrox mixtures are: EAN32 and EAN36, which correspond to 32% and 36% oxygen in the gas mixture.
  

Trimix (TMX)

A mixture of three gases (nitrogen, oxygen and helium) used during technical (decompression) diving. Since oxygen at higher partial pressures is toxic and nitrogen is strongly narcotic - by eliminating their quantity and adding helium, we obtain a breathing mixture suitable for deep dives, during which decompression is required. Divers learn how to choose the composition of the breathing mixture during technical courses. Sometimes recreational divers on diving boats in Hurghada may notice cylinders with a description such as: TMX 16/50. Such a cylinder description means that the mixture contains: 16% oxygen and 50% helium. The percentage of nitrogen is not given, but it can be easily calculated: 34%. The sum of the percentage compositions should give 100%.
  

Oxygen in diving

Oxygen at partial pressures greater than 1.6 ata is toxic to the central nervous system. Exceeding this limit can result in convulsions and, as a result, drowning of the diver. Pure oxygen is used by technical divers during the last stage of technical diving (decompression) at a maximum depth of 6 meters and is used to accelerate decompression, which translates into a shorter time to the safe ascent of the diver. In order to be able to use pure oxygen during dives, one must be appropriately trained in technical diving courses.
  

Recreational divers use air or nitrox (EAN) as their breathing gas.

Technical divers can use trimix (TMX), high (so-called hot nitrox – over 40% oxygen in the mix) and oxygen during the final stage of decompression.

If you read in a newspaper, online portal, or hear in a conversation about a recreational diver who dived with an oxygen tank, this should arouse caution and distrust – the author of the text or statement is certainly not an expert in the field of diving.

At the diving center in Hurghada, during diving courses, we teach what breathing gases are appropriate – how to plan their composition and how to check it.