Nitrox and pressure at depth

[mudchick]

I saw an episode of Deep Sea Detectives in which John dove to something like 125+ feet. His tanks clearly had "nitrox" stickers on them. How is it possible to go that deep on nitrox? A greater percentage of 02 in the mix? Switching from air to nitrox at a non-toxic level?

Also I read about a freediver having gone to 500 feet. I would have thought that wasn't possible. At what depth would the pressure turn a human into a ping pong ball?

 

[DandyDon]

I saw an episode of Deep Sea Detectives in which John dove to something like 125+ feet. His tanks clearly had "nitrox" stickers on them. How is it possible to go that deep on nitrox? A greater percentage of 02 in the mix? Switching from air to nitrox at a non-toxic level?

Nope, a lower percentage of O2 in the tank will make the Nitrox safer deeper. However, even with 32% EANx, the 1.4 MOD is 111 ft, yet the 1.6 MOD is 133. Some dive to 1.6 under otherwise calm conditions.

Also I read about a freediver having gone to 500 feet. I would have thought that wasn't possible. At what depth would the pressure turn a human into a ping pong ball?

I don't know the max free diver depth. Scuba has been taken to 1,000 ft. I would expect a free diver's lungs to be the size of a walnut at 500 ft. :11:

 

[Packhorse]

Nitrox is any mix of Nitrogen & Oxygen. So it could have been 90% N 10 % O.
Or it could have just been normal air in a Nitrox ready tank. Or he could have used it on his accent at shallower depths. Is this program fiction or non fiction?
Max freedive depth is just over 200m (660+ft)

 

[DandyDon]

Max freedive depth is just over 200m (660+ft)

Wow...!!

 

[mudchick]

Then why do you get 02 toxicity w/ nitrox and not when diving regular air?

 

[Packhorse]

You get O2 tox with air too.
At 60m your PPO is 1.47
at 80m your PPo is 1.89

 

[Packhorse]

http://www.scubarecords.com/

 

[ScubaKicker]

I recently saw a program on animal planet called FreeDiver. The woman in it said that her max free dive had been to 525 feet. It was actually a pretty good show if you get a chance its worth the watch.

 

[miketsp]

..snip..
His tanks clearly had "nitrox" stickers on them.
..snip..

The intention of the sticker is just to indicate that the tank may contain a mix different than "normal" air and should be checked with an analyzer before use.
A tank without a sticker should only be filled with air.

So the O2 level could actually be below or above normal.

 

[cummings66]

You can have Nitrox in a tank with no sticker. There are several of us that do that, as long as you have the O2 clean bit on the tank you're fine. The purpose of the sticker is to let others who might take your tank know that it could be dangerous to them if they breathe it.

Some people don't use the traditional stickers and instead use the Voodoo Gas sticker, some have valves on them that say NITROX ONLY.

I guess the lesson is don't use somebody elses tank without permission because it may not contain air.