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Talbot I think:
>> >Is air at 300 bar any less dangerous (from the explosion and dirty
>> >cylinder viewpoint) than 31.5% O2 nitrox at 200 bar? [ie assumes the
>> >pO2s identical]
>>
Me:
>> Most [all?] chemical reactions run at rates given by the product of
>> the concentrations of the constituents.  The implied assumption in
>> the quoted text (above) is correct as far as I can see.  Now there
>> could be differences in details involving the fill but that was not
>> an issue here.
>
Rich:
>I've been asking the same question since the first nitrox workshop in
>Houston, and I have yet to get a satisfactory answer. Most chemical
>reactions are indeed a function of abundance of molecules (i.e., partial
>pressure) not percentage.  The only way that I could understand why air
>has a lower probability of combusting at 300 bar than pure O2 does at 60
>bar was if the N2 somehow buffered or interfered with the combustion
>reaction.
>
>Then Harris Taylor sent me a really interesting article on O2
>combustion.  It was a tad over my head at the time I read it, but the
>gist I got was that combustion probability was a function of BOTH PO2 *AND*
>FO2.  I don't understand it at the molecular level, but there are lots of
>things I don't understand at the molecular level


Take two:
Chemical reactions run on densities (and density products).
The disussion here is revolving around partial pressures.
At pressures where the ideal gas law breaks down the two
concepts are not synonymous.  In fact, the partial pressure
is illdefined.  In my first response I assumed the numbers
had been prepared so that the densities where the same but
if I were to do the math I bet 60 bar of O2 has about the
same density as the O2 in 368 or so bars of air.

Is it possible that this effect can account for all the
observered (?) differences/discrepancies/other ?

john

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