Setpoint value

[inquis]

For deco I fly manual a bit higher

I thought your rational/goal was to stay under the NOAA CNS guidelines, but running higher on deco would put you over, right? (Just trying to understand your position, I'm not making any statements for/against the CNS clock.)

 

[Alekseolsen]

As someone with an upcoming RB class:
For all these "run manual at deco" How does this affect computer TTS value? Does it Calculate based on high setpoint on manual gives you a bit of padding?

 

[BlueTrin]

As someone with an upcoming RB class:
For all these "run manual at deco" How does this affect computer TTS value? Does it Calculate based on high setpoint on manual gives you a bit of padding?

I’d have thought that the one attached to your unit will compute it using the real PPO2 but your backup computer can’t.

 

[Alekseolsen]

I’d have thought that the one attached to your unit will compute it using the real PPO2 but your backup computer can’t.

The real deco - yes, but the tts estimate would be wrong I believe?

 

[BlueTrin]

The real deco - yes, but the tts estimate would be wrong I believe?

Ah you mean that the TTS will be longer because the computer cannot know that you’ll run 1.5 for example manually?

Yes that’s probably correct.

 

[Capt Jim Wyatt]

The computer running in constant PPO2 mode will have a longer TTS because it thinks you are at the HIGH setpoint and not the actual setpoint you are breathing while doing the O2 flushes.

TTS on the actual controller will be accurate because it knows the PO2 you are breathing.

 

[LFMarm]

I thought your rational/goal was to stay under the NOAA CNS guidelines, but running higher on deco would put you over, right? (Just trying to understand your position, I'm not making any statements for/against the CNS clock.)

I use the table to choose my SP High. Given that SP High is only used at the bottom, my average pO2 will be lower than SP High, leaving room for pO2 higher than SP High during deco. Overall average pO2 will be close to SP High.

 

[divingx]

When you run it at 1.3, do you just run it manually at 1.3 during deco with the setpoint at 1.2z

Yeah I just manually run 1.3.

 

[divingx]

Sounds like good advice to me. Although I may get the PO2 up higher at deco, sometimes I switch to an OC 100% O2 bottle to complete the deco.

A small increase in PO2 from 1.3 to 1.4 or 1.5 only removes a few minutes of deco. IMHO it's not worth the increased risk of O2 toxicity.

 

[rjack321]

The computer running in constant PPO2 mode will have a longer TTS because it thinks you are at the HIGH setpoint and not the actual setpoint you are breathing while doing the O2 flushes.

TTS on the actual controller will be accurate because it knows the PO2 you are breathing.

Although the difference 1.1 and 1.2 (for example) end up being almost trivial on modest decos (up to 90mins in the ocean)