Diving shallow on Nitrox.

[NAM001]

Several have hit on the point of tanks with nitrox bands. I have a site that will not fill air in a nitrox tank without charging for nitrox. IE any tank is 8 for air and 16 for nitrox. If the tank has a nitrox sticker that is what they charge. Another site will scrape the sticker if they put air in the tank so you get nitrox or pay the nitrox processing to simplify the process. One site I go to says they do not know if they have air that is e or hyp e. They just get a pass or no pass on the air testing. Since the shop does not deal in nitrox they have no idea, when the air analysis comes back, if it meets hyp e or not. Another site claims that their liability ins does not cover filling nitrox tanks. There are shops that say nitrox is nitrox so 23% is the same as 32% when pricing. Others say banked is one price and custom is another. Nitrox is a hassel in many cases, especially if you own your own tanks.

A final kicker a site with 25' water does nitrox fills. Why cause you cant put air in a nitrox tank. Go figure....................

 

[_Ralph]

If I were to write I'll dive any gas mixture between 18 and 100% oxygen make you feel better?

Just answering an honest question honestly.....

_R

Ralph - How many divers asking this kind of question IN THIS SECTION know what 18/45 is? Just saying...

 

[NAM001]

I've just taken the course, my book says although enriched air reduces the amt of nitrogen you breathe it does not significantly reduce narcosis. Because theoretically oxygen has the same narcotic potential as nitrogen... The current thinking is that the narcosis potential is the same.. And you should plan an enriched air dive accounting for narcosis just as you would regular air. Your susceptibility can change from one dive to the next. My dive instructor is older so he chooses to just dive at a lower PO2 partal pressure..if he dives nitrox (talking deeper dives.. Not 20 ft dives lol) Just for preference.

I am no expert on this but here is my 2 cents. This is an uneducated response. first the idea of o2 is toxic like N2 and should be considered the same when using nitrox as you would trimix. That premis says you are using 100 % toxic mixes any time you dive a nitrox mix, which includes air. My opinioin is that O2 is toxic but not at lower ppo2's . My opinion is also that the toxicity of N2 is felt first then O2. It is possible that O2 is just as toxic as N2 but you have to remember that the PPN2 of the gas is 4 times that of O2. I believe that helium is also toxic but not an the depths (pphe) we are using it at. When you are using trimix you are using it to enable you to go to greater depths where higher pp's of nitrox gasses would be a problem.

As far as lower pp's goes some divers do not dive beyond 1.2 ppo2 where most of us subscribe to 1.4 for planning and 1.6 for contingency. Again some in our midst'st do not dive below eqivilant depths of 100 ft. Hence again the trimix but for dives below 100 ft. I would like to say I have never been narc'd but that is a symptom of being narc'd in it self. Ive dove 160 ft dives and have noticed/remembered no effects on trimix with an equivilant depth less than 100 ft.

 

[TMHeimer]

Re the OP's question-- It has to be as explained--either the tanks were already filled with nitrox and they just took them or they had Air and the yellow band. At 20' or so (I've also heard 18' and 22') you can stay down indefinitely on Air (years if you had enough Air)) and directly surface. Repetitive 20' dives over any number of days would make no difference (I would assume....haven't made a study of it...).

 

[seeker242]

I dive 32% on beach dives just because that's what I always have my tanks filled with. Not because there is anything special about using it at 20'. It's just more simple and convenient to always have them filled with the same mix.

 

[tridacna]

If I were to write I'll dive any gas mixture between 18 and 100% oxygen make you feel better?
_R

Nope. Keep things really simple in this section. And friendly. No need for snark either.

 

[BRT]

I only pump 32%. You won't know cause I don't have bands on my tanks.

 

[halocline]

When diving 20ft on Nitrox, you'll still run out of sir before you run out of time. So, my question is, why would someone still choose to dive nitrox at 20ft?

There's no real benefit for using nitrox on a 20ft dive. But, who knows why people choose to do all sorts of things?

I think GUE (a technical dive agency) basically advocates the use of 32 nitrox for all recreational dives shallower than 110 feet. I'm not 100% sure about it, but I have heard that somewhere. I know that every cave and cavern dive I have done with GUE instructors has been with EAN32, and many of those dives were shallower than 40 ft. It's just something they do.

You'll find that nitrox is very helpful if you ever dive on a liveaboard where you are doing 4 dives/day to 60ft or deeper. It's the repetitive dives where it helps the most in terms of bottom time.

 

[TMHeimer]

I dive 32% on beach dives just because that's what I always have my tanks filled with. Not because there is anything special about using it at 20'. It's just more simple and convenient to always have them filled with the same mix.

Don't you find the extra cost for 32% a concern when Air is just as good at 20'?

 

[gr8jab]

What about those that are on a diving vacation, and slamming 4 tanks/day? Wouldn't 32% help with residual nitrogen loading over multiple repetitive days of diving?

All dives to 20 feet?

Nah, mix and match. While at SCC, I several times did two morning boat dives to various depths, then an afternoon and night shore dive, both at 20-30 feet.

Didn't use Nitrox for the shore dives, but would have if it were cheap...