O2 load up in 24 hours (EANx question).

[HowardE]

Do I keep track of each dive and roll the 24 hour period for each dive and re compute as the dives roll past 24 hours, or does my loading magically vanish after 24 hours and I start every morning fresh? Is there a different chart for this kind of diving? and I read that the chart is covering us for CNS not pulmonary O2 tox, how many types of O2 tox do I need to track?

Basic question how do I safely track O2 over multiple Eanx dives over multiple days, should I just purchase vplanner now?

The first part of your question has been pretty adequately answered. Part 2... Get a good dive computer that not only tracks Oxygen loading, but gives a half-life credit for your SI's. Planning any diving from tables is limiting, because they assume the square profile. If you plan your dives, and stay at 1.4 ppo2 for the planned portion, then basically, you have less than 3 hours total per 24 hour period. Most tables don't mention any credit for O2 half-times. How often do we dive square profiles? Almost never. So the answer to how to safely track your CNS Clock is simply with a nitrox dive computer. Several show your % in actual numbers, rather than just a bar graph.

When I did my deco course I was taught that the half life of CNS toxicity was 90 minutes and I could give myself credit for the surface interval.

For the sake of clarity...The half-life of Oxygen is 90 minutes.

 

[ianr33]

For the sake of clarity...The half-life of Oxygen is 90 minutes.

Is that a ,more or less,scientifically measured number or is it a guesstimate?

Not arguing here,just curious.

 

[HowardE]

I should have said, "half-time"

I was referring to the post by Doc Harry - where he said

half life of CNS toxicity was 90 minutes

More specifically the half-time of O2 is 90 minutes.

From the NOAA CNS table:

While many
authorities suggest that a 90 minute half-time is applicable for surface interval credit
when considering oxygen exposures, such credit is seldom taken into account for
planning recreational dives.

So if you're at 50% after a dive... 90 minutes later... you're at 25%