Piccies please, to appease all of the people you made waste their Friday, and kept us all out of a major ruck, so farpunish myself severly

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Piccies please, to appease all of the people you made waste their Friday, and kept us all out of a major ruck, so farpunish myself severly

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In Physics, just like English, usage does not imply correct usage.

But Physics is less forgiving.

But Physics is less forgiving.

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I was taught a long time ago that p=Pressure. And that P=partial so, more correctly PpO2 is partial pressure of O2.

In addition to this NOAA refer to partial pressure a PP02.

pO2 is the oxygen pressure, if it is mixed with other gasses in a container then you need to take into consideration the fact that the pressure of each gas is equal to the pressure that each gas would produce if it occupied the container alone, thus each gas' individual pressure becomes known as it's Partial Pressure.

How this relates to diving with enriched mixes is something that I don't yet fully understand. Although I do know about O2 toxicity!

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Acording to the IANTD note i have PO2 *Partial Pressure of*

Oxygen in Inspired Gas

Oxygen in Inspired Gas

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32%, written down as a fraction would be 32/100ths, the laws of maths then say that you should round down, so in effect the FO2 of a 32% mix should be written as 8/25ths - never ever seen it written like that......

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Correct, and thanks for reminding me of the correct terminoligy - my old and lunchtime drinking session addled brain couldn't remember "expressed using the lowest common denominator"

But the fact remains - a fraction is written as 36/100 (which would then be expressed as 9/25), not 36% therefore the use of the term FO2 is wrong.

Regards

Stevie H

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Which seems quite appropriative in this case.

You guys are confusing fractions with vulgar fractions.

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Sorry. A vulgar fraction is just the N/M style of representation. Vulgar as in common.Don't think so, vulgar fractions are (unsurprisingly) fractions that are capable of being refined.

It is about style of writing not whether it can be reduced by removing common factors

Never argue mathematics with the physics police.Again, sorry for being pedantic but feel free to shout. It will count towards the course content of my HTFU degree.

"I'd like 9ths in this one please"

"Sorry?"

"9/25ths O2"

The chances of ending up with 9/25 trimix are almost worth it for the laugh at their tiny little brains

Digs.

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It's not wrong really though - as you say, 32% is exactly the same as 32/100, it's just another way of writing it. 32% means 32 out of 100, and 32/100 means 32 out of 100... Even though as you say that the fraction could be simplified, thirty-two one hundredths isn't wrong.

32%, written down as a fraction would be 32/100ths, the laws of maths then say that you should round down, so in effect the FO2 of a 32% mix should be written as 8/25ths - never ever seen it written like that......

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However if you were using fractions it is more sensible to say 8/25 than 32/100.

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PO2 = P x FO2

and

P total = P gas1 + P gas2 + P gas3 ...

The 2nd equation is Dalton's Law ; a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

PO2 calculated in the first equation could be substituted as P gas1 (or PPO2 ) in the 2nd equation.

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