I read some posts about the advantages of using the various EANx mixes. What are the disadvantages or dangers of using these mixtures?
Downside of EANx??
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jetblast00
Contributor
Oxygen Toxicity, both CNS and pulmonary
All Nitrox mixes (including plain 'ol air) have a maximum operating depth (MOD) that is figured based on a maximum partial pressure of O2 you want to expose your body to.
A Nitrox course will teach, among other things, when it's safe to use what ppO2 levels for different situations and the formulas to use that to figure MOD.
All Nitrox mixes (including plain 'ol air) have a maximum operating depth (MOD) that is figured based on a maximum partial pressure of O2 you want to expose your body to.
A Nitrox course will teach, among other things, when it's safe to use what ppO2 levels for different situations and the formulas to use that to figure MOD.
OP
Thank you for the info.
Lost Yooper
Guest
Like anything else, nitrox has rules you have to follow or else you'll die or get hurt.
Availability is still a problem in some places.
Mike
Availability is still a problem in some places.
Mike
Availability: Not everyone has it.
Cost: Its more expensive to buy than air. There are some additional gear costs incurred as well. Tank cleaning for one.
What Jetblast said. You have to watch your depth. Know your max depth and keep a fudge factor on your dive.
Tom
Cost: Its more expensive to buy than air. There are some additional gear costs incurred as well. Tank cleaning for one.
What Jetblast said. You have to watch your depth. Know your max depth and keep a fudge factor on your dive.
Tom
(1) Shallower max safe depth without convulsing and drowning. (alluded to above)
(2) It costs more than air.
(3) It may require special equipment
(4) It may require special equipment maintenence and handling
(5) It isn't as readily available as air (see LY's post)
(6) Its use requires additional training
-----------------
All this will be covered in the course.
Rick
(2) It costs more than air.
(3) It may require special equipment
(4) It may require special equipment maintenence and handling
(5) It isn't as readily available as air (see LY's post)
(6) Its use requires additional training
-----------------
All this will be covered in the course.
Rick
In recent years there has been a dramatic increase in the availability of nitrox. It is an incredibly useful tool even for recreational diving. Any facility that doesn't have and teach nitrox is way behind. Any equipment manufacturer still shying away from nitrox use with their equipment IMO is not worth bothering with. Yes, there are some equipment and dive planning consideration but the benefits are clear and the disadvantages IMO minimal. Do it.
Spectre
Contributor
One of the things you don't learn in an OW class is the concept of Oxygen Toxicity. Yes, you learn the term, and you're told that too much oxygen is toxic, but you never really learn what the deal is.
For every atmosphere you go down, the relative partial pressure of the O2 in your air goes up [typical boyle's law]. e.g. at 33 feet your getting a PP02 of .42; at 130 feet, you're getting the equivalent of pure oxygen. It's fine for the length of time your going to be at that depth, but if you were there for days, you'd start having problems.
Recreational depth limits prevent you from having an issue with Oxygen toxicity. However when you start playing with EANx, those limits change. For example, if your down at 130 ft on 39% O2, your looking at a PP02 of over 1.9, which is definately above the threshold to bring on CNS O2 toxicity (the threshold being 1.6).
When you learn about nitrox, you'll learn about these O2 toxicity thresholds, and you'll end up coming up with a personal threshold. So lets say you take the 1.6 threshold:
((1.6 / .39) - 1 ) * 33 = 102 fsw.
That says you can't exceed 102 feet without exceeding the PPO2 threshold. If your dive is below that, you've got to get yourself a different mix.
Now the _advantage_ comes in with the removed nitrogen. You can use that in two different ways. First, you can use EANx to give you a higher safety buffer in the dive tables, if you stick to dive profiles that fit in the air tables. The second option is using EANx to get longer no-deco limits. For example, if your diving 100 fsw on air, your nitrogen partial pressure is 3.18. On 39% Nitrox, it's 2.46. 2.46 would be equivalent to 70 fsw on air.
Don't trust my math, but hopefully that explains it a little better. And as always, Caveat Emptor... free information is worth the price!
-Jeff
For every atmosphere you go down, the relative partial pressure of the O2 in your air goes up [typical boyle's law]. e.g. at 33 feet your getting a PP02 of .42; at 130 feet, you're getting the equivalent of pure oxygen. It's fine for the length of time your going to be at that depth, but if you were there for days, you'd start having problems.
Recreational depth limits prevent you from having an issue with Oxygen toxicity. However when you start playing with EANx, those limits change. For example, if your down at 130 ft on 39% O2, your looking at a PP02 of over 1.9, which is definately above the threshold to bring on CNS O2 toxicity (the threshold being 1.6).
When you learn about nitrox, you'll learn about these O2 toxicity thresholds, and you'll end up coming up with a personal threshold. So lets say you take the 1.6 threshold:
((1.6 / .39) - 1 ) * 33 = 102 fsw.
That says you can't exceed 102 feet without exceeding the PPO2 threshold. If your dive is below that, you've got to get yourself a different mix.
Now the _advantage_ comes in with the removed nitrogen. You can use that in two different ways. First, you can use EANx to give you a higher safety buffer in the dive tables, if you stick to dive profiles that fit in the air tables. The second option is using EANx to get longer no-deco limits. For example, if your diving 100 fsw on air, your nitrogen partial pressure is 3.18. On 39% Nitrox, it's 2.46. 2.46 would be equivalent to 70 fsw on air.
Don't trust my math, but hopefully that explains it a little better. And as always, Caveat Emptor... free information is worth the price!
-Jeff
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