Question

Why only oxygen not used in tanks used by scuba divers?

Answer 1

At high pressures, the solubility of oxygen increases and leads to excess amount of oxygen in the tissues and cells. This increases the blood pressure and heart rate. High amount of pressurised oxygen leads to oxygen toxicity that can effect the central nervous system(CNS), lungs and eyes. CNS toxicity can lead to convulsions and difficulty in retaining the breath control which can result in drowning of the diver. Therefore, pure oxygen is not suitable for divers unless they have acquired special training. Since oxygen is an excellent catalyst, it can cause the lubricants and materials that come in contact with to explode or burst.
The recreational scuba tanks are filled with compressed, purified air that contains about 30-40% oxygen and 60% nitrogen mixed with some inert gases such as Helium and Argon.