scuba diving deeper than 300 feet

[scubaperro]

If my facts are right, I hear u can only scuba dive down to 300 feet because your air becomes toxic after that. why does it become toxic?

 

[jaybombs25]

check again... people usually don t like diving air below 150... do a bit of research on nitrox,trimix an all these other fun things

 

[do it easy]

In a nutshell, the oxygen at deeper depths has a tendency to cause seizures, which aren't fatal in themselves, but the ensuing loss of consciousness usually is.

To dive deeper, the oxygen has to be replaced with an inert gas, such as helium.

 

[scubaperro]

I heard u can go up to 300 but to stay safe they only do 150

 

[deepstops]

Take the deep diving class.

The oxygen content of air (21%) becomes toxic at 218' (1.6 ata).
7.606 atm X .21 = 1.6 ata Narcosis will kick in much earlier.

 

[Mverick]

If my facts are right, I hear u can only scuba dive down to 300 feet because your air becomes toxic after that. why does it become toxic?

It's called oxygen toxicity. But at 300ft you'll be so narced from the nitrogen you won't care that you die.

Most tech divers don't like going past 90ft on air. They add helium so they remember more of the dive. Narcosis kicks in around 65ft for everyone. Some can deal with it better. Some can't. I know of some very skilled divers who I've dove with many times that swear they don't get narced even in cold water at 120ft. BS, they just can deal with it. It is there.

Oh, sorry.

O2 increases the deeper you go. It relates to partial pressure of oxygen. PPO2 You want to keep that under 1.6. Has a lot to do with Rebreathers but Technical dives did this a long time ago. It's why on deep dive they might only have 10% O2 in some tanks. Because at deep depths it works out to 21%. So, you carry many tanks with different O2 percentages. But, you can't breathe the 10% on the surface or until you reach depth or you'll pass out from lack of Oxygen.

I'm tired just woke up so my explanation stinks. Hope you get it a little.

 

[Thalassamania]

Let’s back up to the facts for a moment.

• In days past a partial pressure limit of 1.8 atm of oxygen exposure was “acceptable” and that’s equivalent to diving air at 250 feet.
• Today that limit has been lowered to 1.6 atm for a resting or decompressing diver (about 210 feet) and 1.4 for normal operations (about 190 feet).
• Nitrogen Narcosis also limits the depth of dives with an effect said to equal one martini, chugged on an empty stomach, for every 60 feet of depth.
• Deeper diving requires specialized equipment and training. Without such equipment and training it is considered prudent to limit the depth of your dives to twice the depth you can free dive.
• Divers wishing to make deep dives may add helium to their breathing gas thus reducing the partial pressure of oxygen and nitrogen and the risks those gases present for a given depth.
• There are individuals who appear to be very resistant to the effects of both nitrogen and oxygen and who have demonstrated the ability to dive significantly deeper than 250 feet using air.
• Tolerance for, and resistance to, the effects of nitrogen and oxygen have been shown to vary widely from individual to individual and even from one day to another.

 

[drbill]

In response to the OP... from what I understand, CNS oxygen toxicity is not usually an instantaneous physiological response but one that depends both on the partial pressure of O-2 experienced and the duration of the exposure. Instantaneous toxicity does occur though at higher levels of pp O-2. Anyone please correct me if I am wrong on that.

I routinely dive to 180-200 feet on air, but my exposure times at those depths are fairly short. I have never reached higher than 5% cumulative CNS oxygen exposure, even on repetitive dives, which I consider to be a safe limit. I seem to have good tolerance to the effects of nitrogen (limited, but perceivable, narcosis even at depth) but don't care to test my tolerance for O-2 toxicity. Different animal.

I would never consider diving on air to depths beyond 200 ft, even for very short durations. And I certainly would never recommend that anyone else dive below recreational depth limits unless they have obtained sufficient training in the procedures to do so, and carry the equipment required to increase the safety of their dives.

 

[Gary D.]

Navy standards were for a max depth of 297' on air and a max WORKING depth of 150 on air in SCUBA.

The matter of fact answers we keep seeing that this or that IS going to happen at a certain depth are not quite as accurate as one might think. Some people can greatly exceed those limits with no ill effects. Others can not even get close to those limits without suffering the same effects. Those limits are for the average person who has not been through serious testing.

So for recreational diving STAY ABOVE OR WITHIN THE LIMITS.

Gary D.

 

[sambolino44]

What if you had a rebreather which keeps the oxygen partial pressure at a safe level, and uses helium for the diluent; how deep could you go, and what would be the limiting factor?