Nitrox problem, is it normal?

[nereas]

Were you using the same regs? Sounds like a reg problem. Maybe not being able to draw well at depth. I wouldnt think the mix would affect how easy it is to breathe. I could be wrong though.... its happened more than once.

Agreed.

 

[Bobby]

What am I calling wrong? The entire concept being taught that you're going to die if you make a dive to 1.4 PPO2! You're even repeating it. You seem to have been taught that 1.4 is the maximum you should ever be at, and should spend 99% of your dive at less than 1.4. What rubish! The 1.4 max was decided upon as the limit for the entire dive. Read your Nitrox book again. Study your tables again. There is a time limit you can spend at 1.4, but even that is a recommendation. You can get hurt with less, you can be fine with more.

Seems to me you make a lot of assumptions. I never stated any concept of someone will die if you pass 1.4 PPO2. I presented a thought process. I was affirming the dive plan and PPO2 in the dive plan. I then went on to add that other variables could give the diver a reason to add more conservatism to their dive planning. I also tried to relay the thought process that higher PPO2's can add to narcosis and/or CO2 retention.

I am a technical diver and will use a 1.6 PPO2 for decompression, it has no bearing on this subject. I also have used a 2.0 PPO2 in the past (NOTE DO NOT EVER USE A 2.0 PPO2) when that was accepted as standard. The Navy has changed their standards for in water max PPO2 along with the rest of the world because of a better understanding of the affects oxygen has on the human body. On more agressive dives most technical divers will lower their PPO2 so they can better manage CNS & OTU's. When on a rebreather for bottom times over 3 hours I will normally run a .9 PPO2 for bottom time. Deco time will be a mix of 1.2 to 1.6 pending the deco profile, CNS build & OTU count for the dive.

There have also been times that I have pushed PPO2's for a specific reason. I would not suggest this to anyone else and have done it strictly as personal choice. You are correct that CNS is a matter of PPO2 & time dose, there is a standard for a reason. There is also a possibilty that the PPO2 level for this dive profile could have contributed to the issue the divers had. They handled the situation very well and asked for thoughts on what could have contributed to the issue. The thought process that I presented was valid and just that a thought process.

Bobby

 

[kalidor's8]

WOW!!!! and GRRRR FSST FSST lol, I did not mean to start a war on here really!

We had set our PPO2 at 1.4 to be on the safe side and our SI was 1hour 45 minutes, so we were well within the tables. I will admit that I have not run my SAC rate yet, but I have been very aware of my rate of breathing. This last weekend was full of firsts for me I will say that much! I have dove this lake many times so was familiar with what it could be like and I was not disappointed that is for sure. I do agree with the rental tank issue but don't have the money to put down for at least 1 dedicated Nitrox tank right now but I am sure that will happen in the future. I am not going to give up on this though I have really grown to love diving (much to my wife's discomfort )

Thanks again guys and if there is anything else you care to throw my way please do I am open to all!

Kev

 

[fire_diver]

WOW!!!! and GRRRR FSST FSST lol, I did not mean to start a war on here really!

Kev

Well, that can happen in ANY thread, regardless of the original post.

As for my comments, I appologize for flying off the handle. Looking back I did make assumptions that were not really there.

I think I just get PO-ed after major cash outlays. And I just had a new heat/air system installed today. I coulda bought a rebreather for the cash I just dropped.

Comrade

 

[Thalassamania]

I never said you would die if you made a dive to 1.4 PP02. I know many spend deco at 1.6 - that being a non-working part of the dive - to maximize o2 exposure to decrease deco times.

I'm well aware of the oxygen clock and calculating you 02 exposure. Everything is scuba is a recommendation, everyone is different, and even what will tox you one day might not tox you the next. I'm also well aware of the PADI Nitrox manual with 1.4 as MOD and 1.6 for contingency. I even said I don't see anything wrong with a nice dive to 110 on 32%, thats what PADI would recommend. However I would say if I knew I was going to be further task loaded or stressed in other ways I would lower my PP02 and aim for 1.2 for the bulk of the working part of the dive.

I've made hundreds of "working" dives using oxygen rebreathers to 30' (that's 1.9), I've made many chamber runs to 60 ft on pure oxygen (that's 2.8), and made hundreds of dives on air to 200 FSW (that's 1.5) and I could not begin to count the number of decompression stops that I've made at 1.9. I think that the current recreational recommendations are more conservative than they need to be.

 

[Buoyant1]

Do your regs have dive/pre-dive venturi controls or adjustable sensitivity knobs on them?

If I don't set mine right for deeper dives (not that I've done a whole lot of them) it gets a bit tough to breathe. (expecially the pre-dive control)

 

[kalidor's8]

His did but mine are pre set by shopI might have to get more training in how to set my own.

 

[Kaiser]

Take You reg in anyway and have it checked! Better safe than sorry. I would NOT recommend to try to adjust the regs if they are not meant to be user adjustable. You might want to look into a balanced regulator like the MK11 and use the MK 2 for Your Stagebottle.

 

[kalidor's8]

had an interesting weekend this last week, spent both days diving. Went to 88ft on Saturday trying to find the sunken town in Lake Travis, never found it but did find the pecan grove that was supposed to be around the town. We figured better to leave the area since it was a tangle of fishing lines. Right after we left I ended up getting the typical signs of narcing so had a little fun there.

On Sunday we did our second Nitrox dive but kept it to about 60ft and had no problems.

Has anyone here ever dived the Valenta site? If someone has maybe you can tell me about how far we were from the town. I will explain the scene as best I can. We followed the "road" from where it enters the lake, then continued straight till the ledge. Went down the ledge and continued to the first few trees. We were able to find a picture from the 30's but it did not have the town in it just the grove and the hilloc that is now an island so not much help there.
Any help would be nice, thanks
Kev

 

[TheWetRookie]

Well, that can happen in ANY thread, regardless of the original post.

Comrade

I enjoy a good debate on a topic so long as we all stay civil and I found this one on PPO2 to be quite interesting, if not benificial in deepening my knowledge. It is also a nice change from the usual "fighting topics" that take place. Now I have to go read and learn more as my curiousity is getting the better of me.

Hmm, let's see, change PPO2 on computer to 3.2 and see what happens... anyone want some new gear?

Thanks guys