What ppO2 do you use and why?

[DuboisP]

Working I will peak at 1.4 ppO2. Most of the dive is below that.

Deco I will peak at 1.6 ppO2 and try minimise time at this level. If conditions allow, I will move my six meter stop to a level between 3 and 5 meters as soon as my deco algorithm allows.

I have done a quick bounce to 1.8 for less than a minute to assist a buddy

computers always set to 1.6 limit.
generally diving under this limit.
already tried 2 under oxygen, without effect, but not without anxiety.

 

[Dehydrated_Atom]

I'm a day late to this but I did not see it mentioned.

Every Air Analyzer I have ever seen will give your FO2/FN2 within a percent. This means that that 32% mix might actually be a 33% mix (could be 31% as well). If you are planning your dive at a 1.6 PPO2, you could easily be actually planning it beyond a PPO2 of 1.6. You may think you are diving at a 1.4, but you may very well be diving at a 1.5. So on and so forth. Bare that in mind when planning your dives.

 

[dfx]

I'm a day late to this but I did not see it mentioned.

Every Air Analyzer I have ever seen will give your FO2/FN2 within a percent. This means that that 32% mix might actually be a 33% mix (could be 31% as well). If you are planning your dive at a 1.6 PPO2, you could easily be actually planning it beyond a PPO2 of 1.6. You may think you are diving at a 1.4, but you may very well be diving at a 1.5. So on and so forth. Bare that in mind when planning your dives.

1% error remains 1% error even at depth. So your 1.4 could become a 1.414 at most. Not a 1.5.

 

[Wookie]

1% error remains 1% error even at depth. So your 1.4 could become a 1.414 at most. Not a 1.5.

Huh? Lets say an O2 analyzer has an error of 1%, so instead of NTX32 you are diving NTX33. For a 130 foot dive, the 32 will give you a 1.58 PPO2. The 33% will give you a 1.63 PPO2. Partial Pressure is not described in terms of percentages, so an analyzer error wouldn't correspond directly with a change in PPO2.

 

[syntaxerrorsix]

In the grand scheme of things 1% variation means very little.

 

[dfx]

Huh? Lets say an O2 analyzer has an error of 1%, so instead of NTX32 you are diving NTX33. For a 130 foot dive, the 32 will give you a 1.58 PPO2. The 33% will give you a 1.63 PPO2. Partial Pressure is not described in terms of percentages, so an analyzer error wouldn't correspond directly with a change in PPO2.

32 vs 33 isn't 1%, that's over 3%.

 

[Wookie]

32 vs 33 isn't 1%, that's over 3%.

Now you have me scratching my head. An Oxygen analyzer has an error of 1% over it's full scale range of 0-100%. That means 32 could read as 33, or 21 could read as 20 and still be within the error of the analyzer. That's what dehydrated atom said in his post. You referenced his post. What are you talking about if it wasn't his post?

I agree with Syntaxerror 6, 1 percent is piddly in the grand scheme of things.

 

[dfx]

Now you have me scratching my head. An Oxygen analyzer has an error of 1% over it's full scale range of 0-100%. That means 32 could read as 33, or 21 could read as 20 and still be within the error of the analyzer. That's what dehydrated atom said in his post. You referenced his post. What are you talking about if it wasn't his post?

I agree with Syntaxerror 6, 1 percent is piddly in the grand scheme of things.

Sorry, I think you're right. Usually when something claims an accuracy of 1%, then that means the real value is within 1% of the measured value. So when you get a reading of 32.0, then 1% of that is 0.32, so that would mean you're within 31.68 and 32.32. But in this case it probably means that the reading is +- 1%, which is something different and makes more sense.

 

[Dr. Lecter]

32 vs 33 isn't 1%, that's over 3%.

True, but irrelevant--we're not talking about realtime O2 monitoring with degree of error expressed in %.

The point made above was most analyzers have a margin of error of =/- 1%: meaning that a tank that is actually 33% may analyze as 32%. Thus, while you set your computer for .32, you are actually breathing .33.

And I see I posted while you were getting that part--sorry

 

[dfx]

Why's there two identical threads going?

http://www.scubaboard.com/forums/advanced-scuba-discussions/461959-what-ppo2-do-you-use-why.html
http://www.scubaboard.com/forums/basic-scuba-discussions/462066-what-ppo2-do-you-use-why.html