PPO2 at altitude?

[Jax]

I just received a new-to-me Predator prot-sa.

I went through the settings and set the altitude to "Auto".

Immediately, the main screen had a flashing red PPO2 of .17.


The computer thinks that Surf is 841, and the now pressure is 841, in milliBars.


Q - is the PPO2 at 5000 feet actually .17? Or is the system in error?

Is this something that will sort itself out over time? The manual has no data on setting the altitude.

The current pressure, according to our weather station, is 29.89 in/merc.


1 inch of mercury = 33.86 millibars

The pressure in millibars should be 1012 millibars at this altitude.

 

[Jim Lapenta]

did you sign up for the dive nav class yet? Might help and the shearwater site is pretty good.

Sent from my DROID X2 using Tapatalk

 

[Jax]

did you sign up for the dive nav class yet? Might help and the shearwater site is pretty good.

Sent from my DROID X2 using Tapatalk

I have! I'm part way through it.

Per the book, it's supposed to be set at "Auto" if you dive at altitude.

 

[Shearwater]

If you are at 5000 feet, then 841 is a normal pressure. That would translate into a PPO2 of .17 if you are breathing air.

Where are you?

Bruce

 

[Jax]

If you are at 5000 feet, then 841 is a normal pressure. That would translate into a PPO2 of .17 if you are breathing air.

Where are you?

Bruce

In my house, at 4990.

---------- Post added at 05:54 PM ---------- Previous post was at 05:54 PM ----------

If you are at 5000 feet, then 841 is a normal pressure. That would translate into a PPO2 of .17 if you are breathing air.

Where are you?

Bruce

Should I, when I get to sea level, set it to sea level, then back to auto? Will that help it calibrate?

 

[Dirty-Dog]

At 5000 feet you're at .843 atmospheres. ppo2 = ata x O2% so
ppo2 = .843 x .21 = .177

A ppo2 of .17 is correct for an altitude of 5000 feet. So it seems to be calibrated correctly. Since it's set to automatically sense and adjust for altitude, when you get to sea level it should show a ppo2 of .21. If not, then you might have a problem, but what you've posted so far indicates that it's working properly.

 

[Jax]

At 5000 feet you're at .843 atmospheres. ppo2 = ata x O2% so
ppo2 = .843 x .21 = .177

A ppo2 of .17 is correct for an altitude of 5000 feet. So it seems to be calibrated correctly. Since it's set to automatically sense and adjust for altitude, when you get to sea level it should show a ppo2 of .21. If not, then you might have a problem, but what you've posted so far indicates that it's working properly.

I figured so, but since a simple conversion of inch/mercury to millibar said the reading should be higher, I thought I'd ask.

It's a bit disconcerting for one's computer to start flashing red right off the bat!

---------- Post added at 06:34 PM ---------- Previous post was at 06:32 PM ----------

Thanks, guys, for the time and reassurance!

 

[rossh]

The public weather pressure readings, are corrected to sea level values. Hence all readings from all cities will be reported in the 1000 - 1030 mb range normally. Those readings actually come from aviation weather observations, and that is the altimeter setting value. At 5000ft, elevation / altitude, your true ambient pressure will be 850 + x mb, depending on about a dozen atmospheric conditions.

Regards

 

[DiveNav]

In my house, at 4990. ......

Where do you dive at 4990ft?

Alberto (aka eDiver)

 

[Jax]

The public weather pressure readings, are corrected to sea level values. Hence all readings from all cities will be reported in the 1000 - 1030 mb range normally. Those readings actually come from aviation weather observations, and that is the altimeter setting value. At 5000ft, elevation / altitude, your true ambient pressure will be 850 + x mb, depending on about a dozen atmospheric conditions.

Regards

Ah, ha!!! So I wasn't going crazy . . . I check my personal weather station, then went to the Air Force Met. data site here, and thought the predator was measuring low.

Never figured out I was at O2 PP of .17 . . . I'm gonna die! :laughing: