Diving shallow on Nitrox.

[Diver-Drex]

All of my cyclinders are labeled as Nitrox cyclinders regardless of the contents. The two places I get fills use only grade e air so the O2 VIP and shoulder band remain valid. But it doesn't mean they are not filled with 21% at times.
I dive EAN on a lot of shallow dives when assisting with students. Typically we'll split large groups up, which can mean 6 "dives" in a day and a lot of ascents when doing CESAs, air sharing ascents and 5 point ascents. Not to mention retrieving students that surface for various reasons. EAN adds some margin for safety.

 

[ljpm]

As many others, I fill after a dive and not before. I therefore put in 32% so I am ready if my next dives are 100'. Additionally, the dive shop where I fill charges the same price for air or 32% ($10, or $7.50 with fill card).

 

[gcarter]

As many others, I fill after a dive and not before. I therefore put in 32% so I am ready if my next dives are 100'. Additionally, the dive shop where I fill charges the same price for air or 32% ($10, or $7.50 with fill card).

We obviously fill at the same place.

 

[Subcooled]

I used to get after dive headaches about 1/2 of the time (not aggressive dives). Since I started diving EAN, this is a very rare occurrence.

Did your air fills contain 2% carbon dioxide? Combustion engines in compressors are evil.
Perhaps the nitrox blending system is cleaner?

 

[tarponchik]

Being an anti-oxygen freak, I do not breath Nitrox unless I absolutely have to. Hey, if only you guys have seen what oxygen radicals do to our DNA like I've seen it in the lab, you'll all become anti-oxygenists!

 

[BRT]

Being an anti-oxygen freak, I do not breath Nitrox unless I absolutely have to. Hey, if only you guys have seen what oxygen radicals do to our DNA like I've seen it in the lab, you'll all become anti-oxygenists!

Probably anyone who is afraid of high partial pressures of O2 shouldn't dive.

 

[tarponchik]

Probably anyone who is afraid of high partial pressures of O2 shouldn't dive.

Yes! As anyone who is afraid of water, darkness, and fish. But why add unnecessary risk?

 

[Caveeagle]

Did your air fills contain 2% carbon dioxide? Combustion engines in compressors are evil.
Perhaps the nitrox blending system is cleaner?

I don't have any reason to suspect this. Most of my diving back then was within a group of 3 buddies, who would all get gas from the same couple shops. If Co2 was the issue, we would have noticed similar issues with other fills from the same banks.

 

[Basking Ridge Diver]

Just for clarification it is CO not CO2 - CO2 is a byproduct of breathing - Carbon Monoxide is exhaust from an engine.

 

[Storker]

Did your air fills contain 2% carbon dioxide? Combustion engines in compressors are evil.

As has been noted, CO2 isn't a huge issue for fills. CO (carbon monoxide) is. CO is evil.

And it really shouldn't have anything to do with whether the compressor is run on a combustion engine or an electrical motor. In any case, the air intake should be well away from the compressor. CO usually comes from incomplete combustion inside the compressor. Sure, have your air intake close to the engine's exhaust and you might well have CO in your breathing gas, but who is stupid enough for that? And how are you going to run your compressor unless it's on a combustion engine if you're on a trip or offshore on a boat?