diving >EANx40

[cky3396]

hello

im scheduled for nitrox classes soon, and im doing some poking around here for more info.. i have a firm graps on nitrox basics at the moment, potential dangers and benefits, etc... but what im struggling to understand at the moment is when a diver will choose anything, lets say, above EANx40? what are the benefits, are they health related? multi-dive day related?

ive read a lot of threads where people say they dive with 100%... howcome?

its my understanding that a diver with a single tank of EANx40 is limited to 25-30 meters to begin with, due to reaching suggested PPo2 limits of 1.4-1.6... and higher ratings will limit a diver to even shallower depths (with increased NDL). doesnt there come a point when any given EANx shows no time benefits because you end up sucking down the cylinder long before you reach the NDL?




thanks all for reading, comments are appreciated!

-joe (trying to absorb as much diving info as possible)

 

[jrc]

Anything above 40% is used for deco. By using a higher O2 you cut down your deco time.

 

[cky3396]

okay, so a diver wont dive with a single tank over 40 for "recreational" dives?

 

[Jimmer]

okay, so a diver wont dive with a single tank over 40 for "recreational" dives?

You got it.

 

[cky3396]

right on, thanks

 

[DA Aquamaster]

Use of mixtures over 40% is normally taught in an Advanced Nitrox class which is in turn normally taught in conjunction with a Decompression Procedures class as the two go hand in hand.

Your observation is correct that for mixtures over 40% the depth where you would have a PPO2 of 1.2 or 1.4 PPO2 is shallow enough that the increased NDL's offered by mixtures over 40% are not that significant compared to what you would get with 36% or 40%.

And of course the other side of the coin is that the depth you can safely dive to with higher percentages is much more limited and it sucks to have a tank full of something you can't use because the dive boat went somewhere deeper than where you originally planned.

 

[String]

doesnt there come a point when any given EANx shows no time benefits because you end up sucking down the cylinder long before you reach the NDL?

Yes.

Depends on the experience (the SAC) of the diver but usually somewhere between 15 and 25m this happens.

EAN50 and above are typically used for accelerating decompression stops so outside the scope of a basic nitrox course. Here they aren't being used to extend NDLs - they have a different purpose.

I wouldn't bother with EAN50 for a shallow dive for example due to the NDL vs air consumption issue but i do use it for deco from 21m/62ft

 

[cky3396]

thanks for the responses guys, much appreciated.

 

[2TH DIVR]

I actually did a dive this summer with a nitrox mix of 82% .( max depth 23')
No use in dumping a good tank $$$
They charge the same to dump a full tank and fill as an empty one.
Yes it is my deco tank

 

[sharkattack]

EANx40 ??????

:no

EANx or EAN40