Who DOESN'T analyze their gas?

[amphipod06]

I got a thermometer for the dive trailer that gives humidity, so that's what I do. (In the summer, 90°F with 90% relative humidity yields 20.0% FO2 in ambient air.)

A thermometer measures temperature...a hygrometer measures humidity...

Back to my rock...

Dive safe,

Celia

[Sludge]

Okay, I got a combination thermometer/hygrometer for the dive trailer...

[PfcAJ]

First, all O2 analyzers actually measure the PPO2, and convert it into a percentage.

Imagine my surprise firing up my "new to me" Predator to find it flashing a red 17 PPO2! I lived at 5000 feet at the time.

So, conversation with Shearwater: All "barometric pressures reported by weather agencies are normalized for the area.".

Now that I moved into town, my Petrel reports .18 . . .

BTW, the Army requires all transferees to have at least 80 days on station before administering a PT test, because it takes time to build the red blood cells to carry the required O2.

Thats because you didn't calibrate it. The % (which is what we're discussing) is the same in all cases. 20.9%. Your ppo2 might be lower, but the % is the same.

http://www.analox.net/reference/RM-0...i_Altitude.pdf

Page 5 is the relevant info.

[Jax]

Shearwater says it is operating exactly as it ought.

[PfcAJ]

So do you think you're breathing 17-18% oxygen?

[a64pilot]

17% O2 at sea level will easily support life, you won't be performing as well during your Marathon, but you won't die either.
What I don't know is at what percent O2 won't support life at seal level pressure, but think it would be a very variable number.
I suspect this knowing Ferry pilots that regularly fly at 18,000 ft. without supplemental O2 and don't even get a headache doing so, I suspect I would go un-conscious trying that.

[Sludge]

I don't know how credible this is, but it says available oxygen in the air in Denver is 18%.

http://www.faqs.org/sports-science/Mo-Pl/Oxygen.html

[Seanmeboy]

On the o2 analyzer they issue at me at work it is .1 6 alarm

[ianr33]

I don't know how credible this is, but it says available oxygen in the air in Denver is 18%.

http://www.faqs.org/sports-science/Mo-Pl/Oxygen.html

That's flat out wrong. The pO2 may well be .18, but that does not mean the %O2 is 18%

[PfcAJ]

Sigh. Science.

What gas makes up the balance if its 18% oxygen in Denver?

I find it interesting that divers (allegedly) understand that at if one is breathing air at 33ft, the ppo2 is .42, and the inspired gas fraction (fo2) is still .21. But the same rules appear not to apply in the other direction?

Less pressure = less ppo2. More pressure = higher ppo2. Same percentage in all cases.