Is my approach to diving with Nitrox logical?

[scubaozy]

Its both time and depth, did you not learn O2 exposure table? At 1.4, you will have 150 mins exposure allowance per day.

 

[Nitrox_DiverNY]

Can you get 36-40% without much hassle? Shops here usually charge a labor fee, plus the gas cost. Plus the 45 min drive each way at least. You have to drop tanks and come back another day. Not worth it. I’ll just take banked 32% which is readily available.

yes at this particular shop its not a hassle, at least not to me. I take what I can get in NY since its not a huge diving hub lol. it is not pre banked so I think any mix needs to be "custom" blended. That is partial pressure blending correct?

 

[jlcnuke]

Air or nitrox, if you're pushing your NDLs, you're nitrogen loading is high. However, diving a safe nitrox mix for your depths, while using air NDLs for the dive, would be how you finish the dive with a 'safer' nitrogen loading.

 

[Nitrox_DiverNY]

At 30-40ft the risk of DCS is so low that 40% is pointless. Mexico cave divers do 2-3 hour dives with average depths in that range using 32% and end with a surface gradient factor (how close they are to the deco required line) of under 10%.

thanks for sharing, how does one determine the gradient factor? do only some computers track it?

 

[Nitrox_DiverNY]

If you go to the limit of NDL for the gas, then you are spending more time under for the same nitrogen load for a person using air going to the air NDL, and your surface intervals will be the same.

I trie not to push anything regardless of gas being used, but that is a good point. thanks. Thought about a second computer to run on air while one is on Nitrox for this reason

 

[Nitrox_DiverNY]

Air or nitrox, if you're pushing your NDLs, you're nitrogen loading is high. However, diving a safe nitrox mix for your depths, while using air NDLs for the dive, would be how you finish the dive with a 'safer' nitrogen loading.

very good point, I have been thinking about running two computers. one air one Nitrox for this reason

 

[Nitrox_DiverNY]

Its both time and depth, did you not learn O2 exposure table? At 1.4, you will have 150 mins exposure allowance per day.

Yes the course I took does include exposure. But I am talking about pulmonary toxicity. not CNS. This specific course was very vague about pulmonary.

 

[Esprise Me]

A buddy of mine does what you do and tries to get the optimal gas for each dive. His nearest dive shop doesn't bank Nitrox, so it's a partial pressure fill regardless, and the only extra hassle is figuring out exactly what percentage he wants based on what dive profile he plans to do next. He's also a little skittish since getting bent while diving the oil rigs a little over a year ago.

I was his buddy on that dive where he got bent; I did not. (The experience still rattled me enough to get me to switch to Nitrox, just not enough to try to get more than 32% on shallow dives.) My local shop banks 32%, and my tanks are not O2 clean, so I just get that. Part of the reason I didn't dive Nitrox much before the DCS incident was that it felt simpler to just always have the same stuff in my tank. I could get it filled whenever it was empty without needing to know what I was going to be doing next. I still operate like that, but I just always get 32% now instead of air. I feel I have enough stuff to keep track of without making things more complicated. But that's just me, not a statement on how I feel others ought to be.

 

[flymolo]

Hello all I am looking for some feedback on my personal diving habits with Nitrox, and to see if my view point on it is incorrect?

Apart from extended NDLs I personally use Nitrox for its potential to reduce nitrogen loading thus contributing to DSC. I am certified up to the standard 40%, and I use as rich as a mix as I can regarding the MOD. For example I am doing dive with a max depth of 30-40ft, and had a cylinder filled as close to 40% as possible it came out to 39.8%. the mod of 40% at a pp02 of 1.4 is 82 ft. My point of view is get the mix as rich as possible as long as its not pushing the MOD at 1.4pp02, and spend the extra money for the extra safety margin, but this practice of using such rich fills seems few and far between. looking at the log book after my fill, it was mostly all 32% with one 36%. It seems like most people just go with the standard 32% even if (in my opinion) their mix cold be richer because they are nowhere near their mod.

The MOD of 40% at 1.4pp02 is around 82 ft, wouldn't using a 40% mix under that depth be a more conservative approach? so if your diving to a Max of 60 why not use 40%? I know DCS in rec is rare, but doesn't it make sense to use rich mixes when the dive allows to add in possible safety? why not be as safe as possible?


Does using a mix like 39-40% pose a substantially bigger risk to Low pressure oxygen toxicity (pulmonary oxygen toxicity), the the standard 32% even if the MOD is not pushed? If someone would be able to enlighten me more about this condition and how common it is with rich nitrox, that would be helpful.

when diving How close to 1.4pp02 will you allow yourself to get? I have never pushed it personally, but how close to 1.4pp02 do you find yourself on dives? do you go right up to it?

Is my logic on using rich mixes valid? Does anyone else share the same view point as me and also go as rich as possible? am I missing something? let me know in the comments, thanks !!

Diving a standard mix like 32% makes it easier to familiarize yourself with ndls for that gas over a range of depths and also makes it easy to coordinate diving the same gasses when diving with buddies/teammates. Diving best mix might also mean you end up with a gas that's too hot if you end up getting redirected elsewhere than where you planned to go.

If you do a lot of boat diving around NY/NJ you'll discover that 28% is actually our local "standard mix".

 

[kelemvor]

Hello all I am looking for some feedback on my personal diving habits with Nitrox, and to see if my view point on it is incorrect?

Apart from extended NDLs I personally use Nitrox for its potential to reduce nitrogen loading thus contributing to DSC. I am certified up to the standard 40%, and I use as rich as a mix as I can regarding the MOD. For example I am doing dive with a max depth of 30-40ft, and had a cylinder filled as close to 40% as possible it came out to 39.8%. the mod of 40% at a pp02 of 1.4 is 82 ft. My point of view is get the mix as rich as possible as long as its not pushing the MOD at 1.4pp02, and spend the extra money for the extra safety margin, but this practice of using such rich fills seems few and far between. looking at the log book after my fill, it was mostly all 32% with one 36%. It seems like most people just go with the standard 32% even if (in my opinion) their mix cold be richer because they are nowhere near their mod.

The MOD of 40% at 1.4pp02 is around 82 ft, wouldn't using a 40% mix under that depth be a more conservative approach? so if your diving to a Max of 60 why not use 40%? I know DCS in rec is rare, but doesn't it make sense to use rich mixes when the dive allows to add in possible safety? why not be as safe as possible?


Does using a mix like 39-40% pose a substantially bigger risk to Low pressure oxygen toxicity (pulmonary oxygen toxicity), the the standard 32% even if the MOD is not pushed? If someone would be able to enlighten me more about this condition and how common it is with rich nitrox, that would be helpful.

when diving How close to 1.4pp02 will you allow yourself to get? I have never pushed it personally, but how close to 1.4pp02 do you find yourself on dives? do you go right up to it?

Is my logic on using rich mixes valid? Does anyone else share the same view point as me and also go as rich as possible? am I missing something? let me know in the comments, thanks !!

When I dive at home, I dive best mix as my favorite local shop blends. $12/tank for a cave filled custom mix is YAY! At destinations like Cozumel, Roatan, FL Keys, etc finding shops that will mix for you is either not possible or ridiculously expensive. Therefore when I travel, I just dive whatever nitrox is being banked. In the Keys it tends to be 30%. In Cozumel and Roatan it was 32%. Supposedly some shops bank 36% but I haven't seen one yet.

So, if you've got a blending shop available then do what you like. I think you'll find they're not extremely common in "destination" locations.

Or, take a tech class or two. Buy a couple bottles of oxygen, and mix your own.

There is one fairly good reason to NOT dive best mix. That is, captains don't always go where they planned on going for a variety of reasons. If you've got 40% in your tank and the captain ends up going to a site that's too deep, you're either going to have to borrow a tank of air (if the boat has extra tanks) or sit out a dive or two. That said, I like the bigger boats and they usually stick to shallow sites (under 60') so it's not likely to be an issue on such boats. It's always good to have a conversation with the teenager booking your dive in advance, and then another one with the captain before you leave the dock just in case.