```At 08:07 21/09/99 -0700, Walt wrote:
>Karen wrote:
>
>>Hmmm... seems this guy is confusing his pony bottle for a
>>stage bottle.
>>Never the twain should meet (unless you have air in both).

Why?

Because a stage bottle might hold (as in your case) a mix that is quite
dangerous in depths where you might need a pony.

(CUT Karen's calculations)

> Wow!!! You got a lot more from a simple statement then I
>did. Now I'm really confused. How do you distinguish a pony
>from a stage bottle?

The names are not important.  They represent different uses.

A pony bottle is a tank that is supposed to be used as an independent sorce
of gas for extended bottom time, bail out in case of primary malfunction
etc. etc.

A stage bottle is supposed to be used as a sorce of gas for decompression
stops.  It usually holds different gas than the bottom mix (usually high O2
percentage, according to the depth it is supposed to be used in).

Your friend who was using a pony bottle with 40% Nitrox was mixing the two.
This could be dangerous because if he dived on air to 40 meters, and had
to use his pony at that depth (remember, a pony is for use when your
primary fails) he would breathe O2 at more than 2.0 ATA.  At this ppO2 -
OxTox is very probable.  It might mean convulsions at 40 meters and if he
is not diving with a full face mask, death is not a out of the question.

With best regards,

Kuty
```