set nitrox mode with stinger suunto ?

Ron MacRae wrote:

> If you want to know then do a nitrox course, otherwise forget it and leave
> the computer in 'air' mode.

Someone really needs to come up with a computer that automatically
defaults to Xenon mode.

This would be very attractive to those that like a big "safety margin"
and it would keep many others out of a lot of trouble.

In article <472db9ab.0408030633.6a7423ec@posting.google.com >,
marmagi@hotmail.com (Mario) wrote:

> interesting none of your answers clearly answer my question, I hope
> there is some one that can seriously explain me the use of setting the
> PO2 from 1.2 upto 1.6
>
>

On all these newsgroups you are posting to no one could answer your
question?

--
I plan my sleep and sleep my plan

I see, now it starts to be more clear.

But I am maybe confussed, doesnt the PO2 depends on the depth ? if it
depends just on the depth why doesnt the computer set it automatically
according to the depth ? or maybe PO2 depends also on other factors?
this is what I would like to understand better.

Thanks,

Mario

> Mario wrote:
> > interesting none of your answers clearly answer my question, I hope
> > there is some one that can seriously explain me the use of setting the
> > PO2 from 1.2 upto 1.6
>
> Current thinking (Lambertson, NEDU) is that there is cumulative damage
> from repeated exposure to hyperbaric O2.
>
> If you plan to do, lifetime, more than a few thousand dives, you may
> want to observe a 1.2 limit to reduce the cumulative damage.
>
> If you plan to do, lifetime, less than a few thousand dives, you need
> only be concerned with the single exposure limits of 1.6 or 2.0 or
> whatever yer church preaches as a single exposure limit.
>
> PADI and others recently reduced single exposure limits from a totally
> arbitrary 1.6 to a totally arbitrary 1.4 in a totally knee-jerk reaction
> to Lambertson's latest work. It is a totally meaningless gesture, but it
> sounds totally cool, and that's what's really totally important in
> recreational scuba.

marmagi@hotmail.com (Mario) wrote in message news:<472db9ab.0408030633.6a7423ec@posting.google. com>...
> interesting none of your answers clearly answer my question, I hope
> there is some one that can seriously explain me the use of setting the
> PO2 from 1.2 upto 1.6

Hardly supprising.
It's OT in rec.scuba (it's not about US politics or guns), and most
people in other groups killfile anything posted to rec.scuba

Alun Harford

Alun Harford wrote:

> marmagi@hotmail.com (Mario) wrote in message news:<472db9ab.0408030633.6a7423ec@posting.google. com>...
>
>>interesting none of your answers clearly answer my question, I hope
>>there is some one that can seriously explain me the use of setting the
>>PO2 from 1.2 upto 1.6
>
>
> Hardly supprising.
> It's OT in rec.scuba (it's not about US politics or guns), and most
> people in other groups killfile anything posted to rec.scuba
>
> Alun Harford

I'd answer him but I don't have a stinger

Mario wrote:
> I see, now it starts to be more clear.
>
> But I am maybe confussed, doesnt the PO2 depends on the depth ? if it
> depends just on the depth why doesnt the computer set it automatically
> according to the depth ? or maybe PO2 depends also on other factors?
> this is what I would like to understand better.

You do need to take a nitrox course.

The PO2 is the fraction of O2 in the mix times the depth in ATA.

At the surface (1 ata) breathing normal air (FO2 0.21) the PPO2 is 1.0 x
0.21 = 0.21 If you are breathing a 40% mix at the surface it is 1.0 x
0.40 = 0.40

At 33 fsw (2 ata) on normal air it is 2.0 x 0.21 = 0.42

At 33 fsw on 40% nitrox it is 2.0 x 0.40 = 0.80