What's your PO2?

[Cave Diver]

A recent discussion in another thread highlighted the difference of opinions among divers on an acceptable PO2 for gas planning. Over the years, I've seen a shift in the recommended max PO2.

I'm a bit curious about the difference in personal attitudes and training on the limits that people use in planning the working portion and deco portion of their dives.

For working portion, do you normally prefer 1.0 or less, 1.2, 1.4, 1.6, or something else?

For the deco portion of your dives do you normally prefer to keep your PO2 at 1.4, 1.6, or something else?

What adjustments (if any) do you make for adverse conditions? (strong current, cold water, etc.)

What is the main driving force in your choices?

 

[Blackwood]

Right now? About .21.

Usually plan for <1.2 max working and ~1.6 max deco. I don't have a good answer for why I make those choices; it's what I was taught. I have not experimented, nor do I adjust based on conditions.

 

[Captain12Pk]

Bottom gas is usually planned at about 1.20.
Deco gas is planned at 1.60.

 

[Chris Brown Tech]

Depends on depth and OC or CCR.

For OC dives up to 150' with no or 'light' deco - 1.5 max backgas and 1.6 deco

Deeper OC dives, 1.4 and 1.6

On CCR - 1.2 for NDL or light deco, 1.1 for deeper/longer dives

 

[Splitlip]

I'm in my fifties. Rec diver.

1.4.

I can dive every day, so I have no problem blowing off a dive.

Good thread.

 

[wedivebc]

1.4 bottom gas 1.6 deco on OC
1.0 dil, 1.3 setpoint, 1.6 bailout (if direct ascent possible) 1.6 deco bailout on CCR

 

[Jax]

Seems like a lot of people like the "1.4 PPO bottom, 1.6 PPO on deco". Is that because it's a fairly often used, well known set of parameters with which people are comfortable?


Are there any of you that does your loading calculations during the dive and deliberately choose your PPO according to the gradient? I know many advanced dive computers let you plug in your M-values.

 

[Kern]

OC, I use a max of 1.4 working, & 1.6 deco, for dives to 55mts; 1.3 working, & 1.6 deco, 55 down to 75mts; 1.2 working, & 1.6 deco, 75 to 90mts. Unless the wreck i'm diving is little more than a debris field, I usually average less than 1.2 to 1 for BT per dive.

I use these mainly for convenience, due to the mix's I use.

 

[Kern]

I use those PPO₂ values in relation to the mix for a particular dive. It's to limit the effects of O₂ & narcosis. Nothing at all to do with decompression. Besides, I'm a VPM person, I don't care about no "M" values.

 

[David_57]

1.4 bottom, 1.6 deco