How does Nitrox work?

[sabbath999]

Here is my point... Dandy Don and I (I'm using him because he often likes to refute things I post on the board) are often on two opposite sides on a debate. In most cases neither of us are wrong per se... but we disagree.

Don has been on the board since 2003... myself a more recent join in 2007. Since 2003, Don has racked up a very impressive 393 thanks for his postings. I admire that because it means Don takes a lot of time to put up useful and thoughtful posts. On average Don receives 65.5 thanks per year since 2003 or more than 1 per week. Now Don has had to make 28,764 postings to receive those 393 thanks or 73.2 posts per one thanks received.

Since joining in 2007, I have totaled 127 thanks... or an average of 63.5 thanks per year (very similar to Don on an annual basis.) The difference is I've only had to make 639 posts to receive those 127 thanks... or just 5.0 posts per one thanks. If I had Don's number of posts, I'd have more than 5752 thanks to his 393.

Not that this indicates I'm better than Don in any way, but rather that I only post relevant... pointed, direct and knowledgeable answers to important questions being asked by divers. i don't come on with a lot of fluff.

Hrmm.... using this as a guage of knowledgable posting, I have been a member of ScubaBoards for 11 months. I have 73 thanks so far out of 275 posts (not counting this one), and projecting that out over a 12 month period that would mean I would probably end up with somewhere around 80 thanks by the end of the year... or, if I get no more thanks for the rest of the year, then we have the firm number of 73 to work off of, which exceeds your average of 63.5 thanks per year, and I am averaging one thanks for only every 3.7671232876712328767123287671233 posts. If I had your number of posts, I would have 169.62545454545454545454545454547 thanks.

Does this mean that I provide more pointed, direct and knoledgeable answers to important questions being asked by divers?

Man, I hope not, since I know SQUAT about diving and I freely admit it.

I always enjoy reading your posts, and I think that you often do have some really good and helpful answers... but brudda, ya missed on this point here.

I also always enjoy reading Don's posts, and have learned a lot from him.

Thanks mean nothing other than warm fuzzies. Hang loose.

 

[MXGratefulDiver]

Extended bottom times are a theory for most recreational divers. What I mean by that is diving Nitrox within recreational limits may allow you to stay down longer - but usually you'll run out of air before reaching the full benefit of diving Nitrox - purely as an increaser of bottom time.

That depends entirely on your dive profile and gas consumption rate. Both can be widely variable.

Paddler3d appropriately pointed out the simplicity in how it works... so I wont reiterate that - the bigger question is do you as a recreational diver need it and is it worth the extra money you'll spend obtaining it?

Generally speaking the answers to those questions for most recreational divers is NO and NO.

I think it would be more accurate to say NO and PERHAPS. The latter question is really going to depend on the individual. This is one area where a diver really has to decide for themselves whether or not the benefit is worth the extra money.

A lot of research has been done on this and everyone who's been diving a while has an opinion on it. DAN (Divers Alert Network) has clearly stated in the past that Nitrox is of little use and little benefit for most recreational divers.

First off, I would dearly love to see where DAN has said such a thing ... and second off, I've long ago learned that you can't take everything DAN says at face value. But I seriously doubt they clearly stated that Nitrox is of little use and little benefit for most recreational divers ... I can't even imagine that they'd take that position.

The exception to this rule is for those doing multiple dives over multiple days... such as on a week long vacation where you're diving 3 or more dives a day for 3 or more consecutive days.

That is one exception ... there are others.

It is not a "deep" gas and in fact becomes dangerous the deeper you go due to the increased risk of oxygen toxicity.

Again, that is an overly broad statement ... because oxygen toxicity is a concern of increased PPO2, which is a function of both the EAN mix and depth. For example, if you are diving to 110 feet or less, EAN32 (a standard nitrox mix) is perfectly safe. So Nitrox CAN be a benefit to the recreational diver on a dive to deeper recreational depths, depending on the dive profile and the EAN mix chosen.

You're welcome to your opinion ... but I really thought this controversy was resolved in the early '90's ...

... Bob (Grateful Diver)

 

[Blackwood]

That depends entirely on your dive profile and gas consumption rate. Both can be widely variable.

Clearly, but OTW was speaking of "most recreational diver," which can be taken to mean "the average diver," who is someone who fits a handful of dives into his vacation itinerary.

For that diver, gas supply is likely the tightest constraint to allowable bottom time.

 

[MXGratefulDiver]

If DAN says it has no benefit for most recreational divers... who am I to disagree.

I have read several things in Alert Diver magazine that I disagreed with. Some of it has even been discussed on ScubaBoard.

My personal experience as it relates to Nitrox. I'm certified and an Instructor in it's use. I've been Nitrox Certified since 2000. I dove it in 2000 and 2001 because back then I didn't know any better. I had been convinced by my LDS I had to have it.

Then I did some research and read articles in DAN's magazine over the years and learned that it was for the most part (and lack of a better term) a bunch of fooey.

I stopped using Nitrox because it cost an extra $100 or more a week on a trip and for tanks locally it was $3 - $5 more per fill if I was diving locally. Based on what I had researched the minimal benefit or lack thereof entirely was not worth the extra investment.

So that sounds more to me like you're saying that for you the benefit isn't worth the extra cost. So you rejected the hundreds of publications that discussed the benefits of Nitrox and listened only to the ones that told you what you wanted to hear (and most likely took them out of context in order to make them fit your criteria).

Now as I've said... it does have it's place in recreational diving... but I even bring that into question and here is why. The only real benefit is an extra added measure of safety... which if you're diving within limits... is minimal.

Depending on how you are using it, the added safety benefits can vary from great to not at all. You just shouldn't discuss this topic in such broad terms ... it helps no one.

My wife and I do liveaboard trips with many friends. They all dive Nitrox except for us. We've been doing it for years now (8 - since 2001.) We all get in the water at the same time, we all do the same dives and we all get out of the water at the same time. Virtually identical profiles. Same surface interval times etc... We'll sometimes do 5 or even 6 dives a day... In the last 8 years there has not been one dive where I couldn't do the exact same profile as any one of them.

Y'all must be doing some very short or very shallow dives then.

Now I'll grant you that my nitrogen loading is higher than theirs... however my loading is still within my computers limits.. and the computers algorythym limits are so conservative they make the Navy Tables look like jumping off a cliff.

Depends on the computer ... there are significant differences between what you'll get for NDL's between brands. I once decided to test this by diving an Oceanic and Suunto strapped side-by-side on my wrist over the course of several dives. I noticed NDL differences as high as 26 minutes for a single dive to recreational depths.

If you're going to put your trust in a dive computer, I would advise that you at least understand the data it's giving you.

I know that putting my post on as I did will draw some attitude from those who push Nitrox on every customer. That is to be expected. They're all out to make a buck and posts like this one don't help that ideology. My posts are there to educate the consumer on the truth. This truth is something they can just as easily obtain through diligent research.

Sounds to me like you're the one with an agenda ... or perhaps just a strong and very outdated opinion.

DAN has been very forthright about Nitrox use in recreational diving and I believe that as one of the top authorities in dive research... theire opinion carries far more weight than mine.

I haven't seen anything from DAN that would support your opinion. If you have data, I would really like to see it.

The whole thing about Nitrox making you feel better after a dive has also been refuted by DAN. At best it has a placebo effect... and I'll agree that may be enough for some people. We all know perception can be far more powerful than reality.

So if you truly believe you feel better because you dive Nitrox - you probably do... but it has nothing to do with the Nitrox...

Cheers to "feel good" diving!

Yeah ... I'm real familiar with the "it's all in your mind" theory. Well, it's MY mind ... and if it makes me feel better, what difference whether it's real or perceived?

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Clearly, but OTW was speaking of "most recreational diver," which can be taken to mean "the average diver," who is someone who fits a handful of dives into his vacation itinerary.

For that diver, gas supply is likely the tightest constraint to allowable bottom time.

OK ... let's talk about that diver.

First off, the whole purpose of nitrox is to put less nitrogen into your system during the course of a dive. And everything that goes into these discussions about safety are based on the assumption of perfect adherence to the rules.

But we all know that the average diver is far from perfect, and only adheres to the rules within the limits of their average ability.

So what is this ability, and what does it mean to the diver?

BY FAR the biggest mistake most average divers make ... and they make it routinely ... is what happens after their safety stop is over. They may ascend nice and slowly up to that point. They will religiously follow the 3 to 5 minute safety stop rule.

Then the safety stop is over, they give their buddy the thumb, and a few seconds later they're on the surface ... little realizing that they just ascended the most important part of the dive at speeds approaching 100 or more feet per minute!

What do you suppose that does to the nitrogen that's still in their tissues?

Even if they're within NDL's ... even if they played everything by the rules up to that point ... they just shook the soda can. Most times they'll get away with it ... the lungs are an incredibly efficient bubble trap. But then they feel awfully tired after the dive is over. Where do you suppose that comes from? Fatigue is one of ... if not THE ... most common symptom of DCS.

Occasionally it'll amount to something worse than a case of fatigue ... and in almost all cases, it'll get chalked up to "undeserved hit", when in fact the diver did it to themselves during the last 10 seconds of the dive.

So where does nitrox fit into all this? Simply put ... the less nitrogen you have inside of you, the less chance you will have of doing that to yourself.

Sure, if you took the entire half-minute (or more) surfacing from your safety stop it wouldn't be a concern. But most "average divers" don't do that ... it never even occurs to them that they should.

... Bob (Grateful Diver)

 

[paddler3d]

Wow.

I've had this discussion with OffTheWallSCUBA1 in the shop. In fact he was the one who certified me in NITROX. We still have this discussion.

I can disagree with 90% of you all on some point or another.

How about we all just agree to disagree and make sure that the original poster got the answer he/she was looking for?

 

[Sas]

Wow.

I've had this discussion with OffTheWallSCUBA1 in the shop. In fact he was the one who certified me in NITROX. We still have this discussion.

I can disagree with 90% of you all on some point or another.

How about we all just agree to disagree and make sure that the original poster got the answer he/she was looking for?

Well people not putting forward their reasoning for disagreeing with 90% of the posts is not very helpful for people who are looking for information about something... If you have legitimate reasons why you disagree with people why don't you post them so others can learn? So far I haven't really found anything convincing in offthewall's posts about why the risks outweigh the benefits of nitrox for recreational divers and seeing as you have ongoing discussions with him about nitrox and were certified by him, perhaps you can explain further?

 

[Cave Diver]

How about we all just agree to disagree and make sure that the original poster got the answer he/she was looking for?

Because this is a discussion board and most of us come here to discuss things. Opposing view points on topics can often bring better understandings to discussions if it can be done civilly.

I can disagree with 90% of you all on some point or another.

Feel free to disagree with what I just said.

 

[paddler3d]

So far I haven't really found anything convincing in offthewall's posts about why the risks outweigh the benefits of nitrox for recreational divers and seeing as you have ongoing discussions with him about nitrox and were certified by him, perhaps you can explain further?

That is just it, I can't. He will give you, what I believe, is a very honest breakdown on his views toward NITROX. There are pros and there are cons, as has been pointed out. He feels there are more cons than pros. So barring Poseidon coming out of the seas and whacking him on the head with his trident, that is what he believes and feels.

Just like you don't feel he has a convincing argument, he feels the same.

If anyone here can convince him other wise, I'll by them a few beers!

 

[Rhone Man]

I am perfectly willing to listen to the "Nitrox is overrated" crowd - I get it from my LDS all the time (mostly because they don't want to invest in the setup). But long term the trend is one way. And there is a reason for that.