Seven Seas | Diving and Swimming Related Info

Diving and Swimming Related: Newspapers and television news often describe open circuit scuba wrongly as "oxygen" equipment, probably by false analogy from aeroplane pilots' oxygen cylinders. Until Enriched Air Nitrox was widely accepted in the late 1990's, almost all sport scuba used simple compressed air. This allowed the scuba industry in the U.S. to bypass being supervised by the Food and Drug Administration (FDA), which defines non-air gas mixtures intended to prevent or treat diseases, as "drugs." Exotic gas mixtures presently used in scuba are intended to prevent decompression illness in diving, but officially, the FDA appears to continue to believe that scuba divers all use compressed air.

At partial pressures over about 1.6 atmospheres, oxygen becomes toxic. Open circuit scuba may supply various breathing gases; but rarely pure oxygen, except during decompression stops in technical diving.

Some divers use Enriched Air Nitrox, which has a higher percentage of oxygen, usually 32% or 36% (EAN32 and EAN36, respectively). This lets them stay underwater longer, because less nitrogen is absorbed into the body's tissues. The most common Nitrox blending method needs an oxygen compatible tank, which is a tank that has had any non-oxygen-compatible grease or rubber removed, by cleaning and replacing parts.

*source: Wikipedia, used with permission