Diving Air vs Nitrox

[tracydr]

Actually, I believe part of the reason divers doing deco take air breaks while on O2 is to reduce pulmonary toxicity.
When I took a 4 1/2 hour chamber ride at 60 feet, I had to take air breaks every 15 minutes. By the 4th hour I was coughing and felt like I was getting a cold. I had definite pulmonary toxicity signs. Not that the average recreational diver will ever do anything comparable, unless they take a chamber ride.
Oxygen is quite toxic to lungs and mucous membranes, worse at increased partial pressures than at 1 ATM.

 

[DevonDiver]

Actually, I believe part of the reason divers doing deco take air breaks while on O2 is to reduce pulmonary toxicity.

PADI TecRec Instructor Manual: Tec45 Knowledge Development:

"Managing Oxygen Exposure

1. Air breaks – These are breaks on air/lower oxygen EANx while decompressing on oxygen or EANx at a depth that yields a PO2 of 1.6 to give your body a rest from the high oxygen exposure.

a. Air breaks have been found to greatly reduce the risk of a CNS toxicity convulsion. Therefore, you should consider them standard practice.
You don’t have to limit them to PO2 of 1.6 bar/ata. Most divers perform air breaks at lower PO2s as well.

The typical air break is five minutes on air (or lowest oxygen gas available) for every 25 minutes of decompression. Do not include the 5 minutes in your decompression time when following a tablesbased accelerated decompression schedule."

 

[maniago]

Thank you, thank you everyone. I'm convinced. We'll get certified on our next trip to Bonaire.

Despite all the machinations and hand wringing above, get the nitrox cert as you have decided.

They can never take it away from you once you have it, but being in a dive location without the cert and really wanting to do the dive like everyone else will have you kicking yourself a long time. Besides, if its a money thing, amortize it per day over the next 20 yrs (because with the current medicines/manufactured replacement parts etal, we're all going to live well over 100 now). Do it and do it right away.

 

[AfterDark]

AfterDark, why don't you work on your air consumption, so that you can make all that money spent on Nitrox worthwhile?

I wish! After 40+ years and >2000 dives I think I've tried everything there is to try. My air consumption hasn't changed much in over 35 years. I think by now it is what is, and that's all it will be. The only sure fire way to extend my bottom time is with doubles! Then it's $28.00 dollars for the 2 NITROX fills, for maybe 1.5 hours of diving. Or $14.00 for the same 2 tanks filled with air. I can get 3 or more hours of diving air for $28.00. I thought I'd be using NITROX down NC this year but the weather was so bad we didn't know if we'd be diving 60fsw inshore or 100+fsw offshore until we were out on the water, the only safe bet was air.

Edit: Maybe use my scooter on every dive! Cheap toy wouldn't last too long.

 

[maniago]

I wish! After 40+ years and >2000 dives I think I've tried everything there is to try. My air consumption hasn't changed much in over 35 years. I think by now it is what is, and that's all it will be. The only sure fire way to extend my bottom time is with doubles!

A set of gills is good too....!

 

[Malpaso]

Nitrox cert requires no diving, just classwork and classroom demo of analyzing a tank.

I'm looking to get my Nitrox certification before going to the Turks in August.
1. The classroom is revisiting gas laws, and learning a new set of tables?
2. When you get a Nitrox fill, do you (the diver) analyze the tank, or do you observe/verify the shop analyzing it? I can't imagine you (the diver) owning your own analyzer.

 

[danvolker]

Yes, a new set of tables....you could learn this with half of your brain removed, and after drinking a 5th of Jack Daniels...and yet, they won't include this in OW training.....The reason, is that it is a PROFIT CENTER. It costs the shop almost nothing, and you will pay good money for this in order to get more enjoyment out of diving.

You really should be the one to analyze your tanks.....you don't trust this to anyone else....you will learn how in the class...( you could teach a chimpanzee to do this), it is not hard....
The downside of letting the shop do it, and not checking yourself, is that someone not paying attention, or not caring, could easily not really analyze your mix.....or it could be significantly off.

The shop will have an analyzer you can use, and that is fine......some of us bought our own, so that if we go on a boat that has nitrox for us, we can still analyze our own tanks.....very easy, but very necessary .

 

[maniago]

2. When you get a Nitrox fill, do you (the diver) analyze the tank, or do you observe/verify the shop analyzing it? I can't imagine you (the diver) owning your own analyzer.

Imagine it because yes, yes you do. Or you should. In fact I'll add that its thought of as a bit odd if you don't. Though you can use the shop ones if you want, think about the abuse they take and whether you the gas breather are willing to trust them with your life. The LDS is not expecting you to trust them on this; they are expecting you to verify what they read.

There are horror stories on badly wrong shop analyzers. Its probably low risk, but like the lottery, it only takes one.

 

[tracydr]

Andy, does that mean you're not also resting your lungs? Or just that the only reason PADI has you break is to prevent CNS exposure?
I know the main reason is of course to prevent CNS toxicity but I've always thought that resting for a pulmonary break was a secondary reason. I certainly needed it for my respiratory tissues during my chamber ride.
I know that when reading Vern Van Schaik's book, she talked about experiencing pulmonary O2 symptoms after her long deco run. It scared her quite a lot because at the time, she didn't know what it was caused from.

---------- Post added July 13th, 2013 at 12:24 PM ----------

Yes, a new set of tables....you could learn this with half of your brain removed, and after drinking a 5th of Jack Daniels...and yet, they won't include this in OW training.....The reason, is that it is a PROFIT CENTER. It costs the shop almost nothing, and you will pay good money for this in order to get more enjoyment out of diving.

You really should be the one to analyze your tanks.....you don't trust this to anyone else....you will learn how in the class...( you could teach a chimpanzee to do this), it is not hard....
The downside of letting the shop do it, and not checking yourself, is that someone not paying attention, or not caring, could easily not really analyze your mix.....or it could be significantly off.

The shop will have an analyzer you can use, and that is fine......some of us bought our own, so that if we go on a boat that has nitrox for us, we can still analyze our own tanks.....very easy, but very necessary .

Since tables aren't taught in OW classes anymore, its the first intro to tables many divers ever have. This can be quite difficult for many newer divers without having a good mentor to explain it.
wonder if there's a YouTube lecture on using dive tables?

---------- Post added July 13th, 2013 at 12:26 PM ----------

I'm looking to get my Nitrox certification before going to the Turks in August.
1. The classroom is revisiting gas laws, and learning a new set of tables?
2. When you get a Nitrox fill, do you (the diver) analyze the tank, or do you observe/verify the shop analyzing it? I can't imagine you (the diver) owning your own analyzer.

Have you tried yoga classes? Learning proper breathing technique from yoga can make a difference. Many people don't know how to breathe. I see it in my practice a lot. If yo raise your shoulders with a breath instead of sticking your stomach out that could be the issue.

---------- Post added July 13th, 2013 at 12:28 PM ----------

There are some dive trips where nitrox is really important. Galapegos comes to mind. I think they may have required it on our boat.

 

[reefduffer]

I'm looking to get my Nitrox certification before going to the Turks in August.
1. The classroom is revisiting gas laws, and learning a new set of tables?

Disclaimer: I'm going to give a straightforward answer to your reasonable question, but my answer is in no way a substitute for the training associated with the cert.

Yes, some of it is new tables and the concept of equivalent air depth so you can do the N2 calculations for a %O2 that you don't have tables for. A review of nitrogen loading, and high school algebra.

Then the concept of oxygen toxicity, why it presents new dangers you won't encounter at recreational depths on air, and the new limits (mostly max depth) it puts on your diving.

Also, the new dangers that can exist with a high O2 environment and associated equipment at the surface, including some additional requirements on regulators etc. that you should be aware of, although they will likely be transparent to you.

And then the protocols for dealing with EAN mixes, tank labeling, etc., that have been developed to prevent the injuries that could occur from diving with a different mix than you think you are. Including tank analysis.

That's an overview, not a course summary. Take the class.

2. When you get a Nitrox fill, do you (the diver) analyze the tank, or do you observe/verify the shop analyzing it? I can't imagine you (the diver) owning your own analyzer.

Yes, the protocol includes the requirement that you analyze every EAN tank you dive, and log the contents. No, most Nitrox divers don't have their own analyzers; the operator provides one for the divers to use. I don't have my own. From memory, I've dived nitrox with 5 different operators (some on multiple vacations) and every one had an analyzer for guest use (sometimes several), and expected you to use it.