Nitrox Certification – Dive Longer

Why Dive with Nitrox?

During scuba certification, you learned how the water pressure at depth causes nitrogen from the tank air you’re breathing to dissolve into your bloodstream. The higher the pressure (depth), the more nitrogen will dissolve. After a certain concentration of nitrogen builds up, you must come back to the surface slowly, and then spend time outside of the water allowing the nitrogen to leave your body. Diving with Nitrox changes this.

According to U.S. Navy dive tables, a diver on air at 100 feet reaches his or her no-decompression limit and must come up after 25 minutes, regardless of how much air is left in the tank. At 60 feet, the diver’s maximum time would be one hour.

Breathing with Nitrox tanks replaces some of the nitrogen with extra oxygen, so less nitrogen is available, which allows a longer no-decompression limit. This is known as the equivalent air depth (EAD). If you were to dive to 105 feet with 36 percent Nitrox, the numbers relating to how nitrogen is dissolving into blood and tissues is more like diving at 80 feet. This changes the no-decompression limit of 20 minutes to 40 minutes and doubles your bottom time.

Diving shallower than 50 feet allows for longer bottom times and divers use up their air before their bottom time runs out so in this case, Nitrox is not beneficial on shallow dives. However, when diving in the 50 to 100 foot range, Nitrox can sometimes double bottom times. If you use Nitrox at 60 feet, where the normal bottom time is 50 minutes, the no-decompression limit can extend to 130 minutes.

Enriched Air Nitrox (EAN) refers to any nitrogen/oxygen gas mixture with an oxygen concentration higher than the 21 percent found in normal air. Most commonly, this will be 32 percent oxygen. It is this higher percentage of oxygen, and the proportionately lower percentage of nitrogen, that allows divers to lengthen no-decompression limits, shorten surface intervals and enjoy an added safety buffer on decompression sickness.

Our Nitrox course takes one and one half days to complete. It includes full equipment, two ocean dives at a maximum of 40% oxygen and to a maximum depth of 110 feet/30 meters.

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