Talk:Depth Levels/@comment-27658215-20160122224315/@comment-84.211.183.78-20160229140500

In deep-diveing, the part-pressure of oxygen is lowerd in the mixture gas, to avoid oxygen-narcosis. The N2 is replased by helium or even a 3 part mix of, He,H2 , and O2. But due to the Much higher total pressure the consumption of O2 actualt increases. At some 300m (the deepest Nort-sea dive), a normal pressuretank would only last a few minutes. Say your lungvolume is 4liters, at 30 ATM , you would use 120 l Gas each time you fill your lungs. 2x10 liter bottles at 200 Bar equals 4000 liters of gas. You would empty  that in 33,3 breats. (in deep duiving they use 300 Bar tanks tho, so 6000l instead of 4000 still.... )