origin of the constant values in the EAD and PO2 formula calculations ?

I blame the instructors.

They either can't teach properly, or if they have a student who simply can't
do the maths, then they haven't got the balls to be honest and fail
someone!


"Keith Lawrence" <false@nospam.com> wrote in message
news:411742de$0$58823$5a6aecb4@news.aaisp.net.uk.. .
> "Mario" <marmagi@hotmail.com> wrote ...
>
> > Can some one explain me or tell me a web link in which is explained
> > the origin or source of the formulas for calculating:
> >
> > EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> > 0.79 comes from where?
> >
> > PO2=(((Depth+10))/10)x 02%
> >
> > this formula comes from where?
> >
> > I would like to understand where these formulas come from.
>
> Your basic diving course and the Nitrox course should explain it.
>
> The 0.79 comes from the N content of ordinary air, around 21% O2, 79% N
>
> The Depth + 10 =MUST= be in metres, the +10 (then / 10) gives you the
> additional 1 BAR pressure of the atmosphere to give you the absolute
> pressure at depth. e.g. 10m of water gives you (10 + 10) / 10 = 2 BAR
> absolute.
>
> HTH, do the course
>
> Keith L
>
>

I blame the instructors.

They either can't teach properly, or if they have a student who simply can't
do the maths, then they haven't got the balls to be honest and fail
someone!


"Keith Lawrence" <false@nospam.com> wrote in message
news:411742de$0$58823$5a6aecb4@news.aaisp.net.uk.. .
> "Mario" <marmagi@hotmail.com> wrote ...
>
> > Can some one explain me or tell me a web link in which is explained
> > the origin or source of the formulas for calculating:
> >
> > EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> > 0.79 comes from where?
> >
> > PO2=(((Depth+10))/10)x 02%
> >
> > this formula comes from where?
> >
> > I would like to understand where these formulas come from.
>
> Your basic diving course and the Nitrox course should explain it.
>
> The 0.79 comes from the N content of ordinary air, around 21% O2, 79% N
>
> The Depth + 10 =MUST= be in metres, the +10 (then / 10) gives you the
> additional 1 BAR pressure of the atmosphere to give you the absolute
> pressure at depth. e.g. 10m of water gives you (10 + 10) / 10 = 2 BAR
> absolute.
>
> HTH, do the course
>
> Keith L
>
>

I blame the instructors.

They either can't teach properly, or if they have a student who simply can't
do the maths, then they haven't got the balls to be honest and fail
someone!


"Keith Lawrence" <false@nospam.com> wrote in message
news:411742de$0$58823$5a6aecb4@news.aaisp.net.uk.. .
> "Mario" <marmagi@hotmail.com> wrote ...
>
> > Can some one explain me or tell me a web link in which is explained
> > the origin or source of the formulas for calculating:
> >
> > EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> > 0.79 comes from where?
> >
> > PO2=(((Depth+10))/10)x 02%
> >
> > this formula comes from where?
> >
> > I would like to understand where these formulas come from.
>
> Your basic diving course and the Nitrox course should explain it.
>
> The 0.79 comes from the N content of ordinary air, around 21% O2, 79% N
>
> The Depth + 10 =MUST= be in metres, the +10 (then / 10) gives you the
> additional 1 BAR pressure of the atmosphere to give you the absolute
> pressure at depth. e.g. 10m of water gives you (10 + 10) / 10 = 2 BAR
> absolute.
>
> HTH, do the course
>
> Keith L
>
>

"Pete Melbourne" <psmvsl@yahoo.co.uk> wrote in message
news:o1jeh0p21k28g93kqt4fga2kot5nd55r07@4ax.com...
> On 9 Aug 2004 02:13:55 -0700, marmagi@hotmail.com (Mario) wrote:
>
> >Hello,
> >
> >Can some one explain me or tell me a web link in which is explained
> >the origin or source of the formulas for calculating:
> >
> >EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> >0.79 comes from where?
> >
> >PO2=(((Depth+10))/10)x 02%
> >
> >this formula comes from where?
> >
> >I would like to understand where these formulas come from.
> >
>
> It is all Dalton's Law which you should have been taught in your basic
> scuba and Nitrox courses

I didn't know that peanuts were involved! Where'se Percy?

--
> Pete
>
> news 'at' melbourne 'dot' me 'dot' uk

"Pete Melbourne" <psmvsl@yahoo.co.uk> wrote in message
news:o1jeh0p21k28g93kqt4fga2kot5nd55r07@4ax.com...
> On 9 Aug 2004 02:13:55 -0700, marmagi@hotmail.com (Mario) wrote:
>
> >Hello,
> >
> >Can some one explain me or tell me a web link in which is explained
> >the origin or source of the formulas for calculating:
> >
> >EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> >0.79 comes from where?
> >
> >PO2=(((Depth+10))/10)x 02%
> >
> >this formula comes from where?
> >
> >I would like to understand where these formulas come from.
> >
>
> It is all Dalton's Law which you should have been taught in your basic
> scuba and Nitrox courses

I didn't know that peanuts were involved! Where'se Percy?

--
> Pete
>
> news 'at' melbourne 'dot' me 'dot' uk

"Pete Melbourne" <psmvsl@yahoo.co.uk> wrote in message
news:o1jeh0p21k28g93kqt4fga2kot5nd55r07@4ax.com...
> On 9 Aug 2004 02:13:55 -0700, marmagi@hotmail.com (Mario) wrote:
>
> >Hello,
> >
> >Can some one explain me or tell me a web link in which is explained
> >the origin or source of the formulas for calculating:
> >
> >EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
> >
> >0.79 comes from where?
> >
> >PO2=(((Depth+10))/10)x 02%
> >
> >this formula comes from where?
> >
> >I would like to understand where these formulas come from.
> >
>
> It is all Dalton's Law which you should have been taught in your basic
> scuba and Nitrox courses

I didn't know that peanuts were involved! Where'se Percy?

--
> Pete
>
> news 'at' melbourne 'dot' me 'dot' uk

Hello,

Can some one explain me or tell me a web link in which is explained
the origin or source of the formulas for calculating:

EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10

0.79 comes from where?

PO2=(((Depth+10))/10)x 02%

this formula comes from where?

I would like to understand where these formulas come from.

Thanks,

Mario

"Mario" <marmagi@hotmail.com> wrote ...

> Can some one explain me or tell me a web link in which is explained
> the origin or source of the formulas for calculating:
>
> EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
>
> 0.79 comes from where?
>
> PO2=(((Depth+10))/10)x 02%
>
> this formula comes from where?
>
> I would like to understand where these formulas come from.

Your basic diving course and the Nitrox course should explain it.

The 0.79 comes from the N content of ordinary air, around 21% O2, 79% N

The Depth + 10 =MUST= be in metres, the +10 (then / 10) gives you the
additional 1 BAR pressure of the atmosphere to give you the absolute
pressure at depth. e.g. 10m of water gives you (10 + 10) / 10 = 2 BAR
absolute.

HTH, do the course

Keith L

"Mario" <marmagi@hotmail.com> wrote in message
news:472db9ab.0408090113.5dc1cb28@posting.google.c om...
> Hello,
>
> Can some one explain me or tell me a web link in which is explained
> the origin or source of the formulas for calculating:
>
> EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10

That's the formula in meters. Most here are more likely to do the formula
in feet.

> 0.79 comes from where?

That's the partial pressure of nitrogen at 1 atmosphere

> PO2=(((Depth+10))/10)x 02%

> this formula comes from where?

The partial pressure of O2, and other gasses as well, varies with depth.
The sum of all partial pressures will always equal the the total pressure.
In the formulas you've shown, the gas is presumed to consist only of
nitrogen and oxygen at .79 and .21 percent respectively for air. At 10
meters, approximately 2 atmospheres, you're talking partial pressures of
1.58 and .42 which, you'll note, add to 2 atmospheres.

Lee

On 9 Aug 2004 02:13:55 -0700, marmagi@hotmail.com (Mario) wrote:

>Hello,
>
>Can some one explain me or tell me a web link in which is explained
>the origin or source of the formulas for calculating:
>
>EAD= (((1-O2%) x (Depth+10) )/ 0.79)-10
>
>0.79 comes from where?
>
>PO2=(((Depth+10))/10)x 02%
>
>this formula comes from where?
>
>I would like to understand where these formulas come from.
>

It is all Dalton's Law which you should have been taught in your basic
scuba and Nitrox courses
--
Pete

news 'at' melbourne 'dot' me 'dot' uk