Nitrox - 1.40 or 1.60 PO2?

[scjoe]

Although NOAA does not follow the half time credit and treats the oxygen exposure as all disappearing at once after 24 hours, its statement that the credit is seldom taken into account for recreational diving is wrong. You can find a 24 hour limit for 1.6 of 150 minutes in DAN and IANTD and I believe SDI/TDI materials. Also, I think many of the computers on the market do give you surface interval credits.

 

[Chad Carney]

So what's wrong with 1.5 PO2 as a compromise?

There's a huge change in the O2 single dive limit when backing off from 1.6 to 1.5, and only a slight change from 1.5 to 1.4, and you retain 2% more nitrox. Isn't that what it's all about in the first place?

I'm a spearfisherman and rarely bottom out, so I'm usually at 1.4 most of the time when I'm mixed for 1.6, and real glad to have all the nitrox I can get. Technical spearos tend to do more dives in a day than other divers, like 4 to 8 commonly.

Chad

 

[ZenDiver.3D]

Caver,
Yes, I am doing recreational diving.

Thanks for replying.

Textbook answer= use up to 1.6 for shallow, easy dives.
use 1.4 for more strenuous, colder water, or new condition dives.

Conservative can never be bad.

And you are a recreational diver. Don't exceed your MOD and use 1.4 for a good while. Also, study more. You really want to understand the ins and outs completely. It is worth it. Good luck.

 

[freshwater]

Great article Papa bear!

 

[jtivat]

The more I learn and the more I dive deep the lower I am willing to go. I try and keep my bottom PP at 1.2 and might hit a 1.3 max. Not sure what is right or wrong but not sure I am willing to suffer the consequences pushing it higher and being wrong. The benefit of saving a few minutes of deco or a few extra minutes of bottom time is just not worth it. I really do not get this big push to increase your PP O2?

 

[HowardE]

So what's wrong with 1.5 PO2 as a compromise?

There's a huge change in the O2 single dive limit when backing off from 1.6 to 1.5, and only a slight change from 1.5 to 1.4, and you retain 2% more nitrox. Isn't that what it's all about in the first place?

I'm a spearfisherman and rarely bottom out, so I'm usually at 1.4 most of the time when I'm mixed for 1.6, and real glad to have all the nitrox I can get. Technical spearos tend to do more dives in a day than other divers, like 4 to 8 commonly.

Chad

1.5 PPO2 offers you 2 hours maximum of dive time in a 24 hour period.

Food for thought.

 

[Rhone Man]

Always remember, oxygen toxicity threshholds are an inexact physionlogical science. Don't confuse precision (numbers and formulae) with accuracy.

 

[HowardE]

The guidelines set forth in PO2 exposure are just that. The thing that people seem to continuously confuse, is that exceeding an "MOD" will cause immediate oxtox or death. that is just not the case.

People are frequently subjected to 2 ATA's of O2 in decompression chambers for 1/2 hour without toxing.

 

[netmage]

So what's wrong with 1.5 PO2 as a compromise?

There's a huge change in the O2 single dive limit when backing off from 1.6 to 1.5, and only a slight change from 1.5 to 1.4, and you retain 2% more nitrox. Isn't that what it's all about in the first place?

I'm a spearfisherman and rarely bottom out, so I'm usually at 1.4 most of the time when I'm mixed for 1.6, and real glad to have all the nitrox I can get. Technical spearos tend to do more dives in a day than other divers, like 4 to 8 commonly.

Chad

Only in so far as there have been a few incidents recently where people had fatal adverse reactions @ 1.4.....

Technical spearos also are doing significantly shorter bottom times, likely bounces - no...?

 

[Apexmedic]

Here is what I was taught and its a good rule to go by. Know what your Po2 depth is for 1.6 but set your computer to 1.4. Keep in mind both depths, use 1.4 as your plan, and if you happen to go "deeper" for some reason like dropping your camera an extra 5-10' and your still in your "max" depth for 1.6 then your ok. Its a "Safety barrier" Thats how I was taught and I go by it. I try to stay well within my 1.4 range and never flirt with my 1.6. Dive to what makes you comfortable, if your instructor told you to use 1.4 then stay with it, its what your comfortable with. Getting a hit is not worth it. :mooner: