Reasons NOT to use Enriched Air?

[Blackwood]

Or am I confusing that with being narced?

Yes you are.

 

[Gombessa]

If you feel narced, ascending slowly is supposed to help "clear your head" pretty quickly. I think the onset of oxygen toxicity is sudden loss of consciousness and involuntary seizures. It's hard to self-rescue from that. I'm sure some more knowledgeable members can say whether there are any indicator or precursor symptoms.

 

[hypertech]

I removed the bad info from my post - I was confused.

I'd agree on the CON part of CONVENTID, but I think you might be able to recognize the VENTID part coming on. I am admittedly finding myself a little fuzzy on this ....

 

[tschmitt]

I was gonna say that diving nitrox beyond the MOD will either get you in a hospital or in a graveyard, but you beat me to it.

You're more likely to end up buried than in the hospital. Seizures as a result of OxTox are not particularly harmful aside for the small and unfortunate side effect - spitting out your reg and sucking down water...

One of my main fears when diving Nitrox is a strong down current. Mainly cos I tend to end up around 30m in strong currents, tho usually on 32 rather than 36. But still around the 1.4 area. Which is very safe. But wouldn't be ten metres lower. That is my main reason why I have to think about whether to dive Nitrox or not.

Really it's a very specific depth range. Between 20 and 30m it rocks. Shallower than that what's the point given the expense. Deeper than that you need to rethink. So in that 10m zone (which for recreational diving is a BIG zone) it's great.

Personally I love it but when I get near the limit it does up my anxiety a little.

J

The MOD of 1.4 ATA is pretty conservative, but I'm not sure I want to dance with the devil either. If I'm doing a bunch of dives at 40-90 ft. I prefer EANx. Personally, I do not get as tired after repetitive dives on it as I do with Air. 90ft and below, Air only for me.

 

[Blackwood]

If you feel narced, ascending slowly is supposed to help "clear your head" pretty quickly. I think the onset of oxygen toxicity is sudden loss of consciousness and involuntary seizures. It's hard to self-rescue from that.

Not to mention that ascending won't necessarily stop or prevent a seizure.

People have toxed well after leaving the maximum PO₂.

90ft and below, Air only for me.

Interesting... that's close to the depth (120+) at which I'll no longer consider air as a viable gas.

 

[tschmitt]

Not to mention that ascending won't necessarily stop or prevent a seizure.

People have toxed well after leaving the maximum PO₂.

If you aren't at 100% of your O₂ Clock and simply a CNS seizure from a high PO₂ then ascending will likely reverse the seizure. If you've been diving on EANx all day and you're pushing 100%+ O₂ toxicity, you probably even run the risk of seizing at the surface.

Interesting... that's close to the depth (120+) at which I'll no longer consider air as a viable gas.

Sorry, I meant to Rec dive limits.

 

[Anti-Hero]

1.4 ATA is VERY conservative. I personally do not exceed 1.4, but many navy divers at one point in time pushed the 2.0 ATA limits. I think 1.4 is made exceptionally safe so the general recreational community isn't toxing left and right; opening PADI, et. all up to lawsuits.

 

[Blackwood]

If you aren't at 100% of your O₂ Clock and simply a CNS seizure from a high PO₂ then ascending will likely reverse the seizure.

I'm not sure about that...

In fact, I'm not sure if anyone is sure about that

 

[nereas]

...Question: Is there any reason why I should not use Enriched Air for every dive? Is there a reason why I would want to sometimes use AIR opposed to Enriched Air?

From my studys in the Nitrox class it seems ok for me to just stick to Enriched Air whenever I can...

If you are diving really shallow, such as 20 to 50 ft along the coast or in the tropics, then EANx would be a waste of oxygen and money. The only time that diving shallower than 50 ft would make sense with nitrox would be for diving in the mountains (high altitude).

The general rule is that EANx is ideal, and better than air, for any depth between 50 ft and 150 ft.

For dives in the range of 50 ft to 95 ft, EAN 36 is the best mix.

For dives in the range of 100 ft to 130 ft, EAN 32 is the best mix.

For dives in the range of 130 ft to 150 ft, EAN 25 is the best mix. However this is normally considered a technical deco dive, since your NDL would only be 5 mins.

For anything deeper than 150 ft, you whould be diving with trimix, and now you would be outside the range of nitrox.

A basic nitrox certification would allow you to use EAN 36 or EAN 32, for diving to depths of 130 ft (or shallower, per the above limits).

 

[nereas]

If you aren't at 100% of your O₂ Clock and simply a CNS seizure from a high PO₂ then ascending will likely reverse the seizure. If you've been diving on EANx all day and you're pushing 100%+ O₂ toxicity, you probably even run the risk of seizing at the surface.

Sorry, I meant to Rec dive limits.

With 1 hour surface intervals, like you were taught in your basic open water class, you will not be able to add up sufficient CNS to affect your CNS OxTox risk, one way or the other.

CNS Ox Tox is only a risk if you dive too deep with nitrox. That is why 90 ft and 130 ft are the depth limits taught for EAN 36 and EAN 32, respectively.

An IF you do have a seizure, then you are dead. There is no chance to ascend to "reverse the seizure."

With nitrox, you need to make sure you obey your depth limits, and you need to make sure you allow a 1 hour surface interval between repetitive dives.