[dynarob]

I have always taken them to mean the same thing ie Partial Pressure of Oxygen

Coming from another thread it is apparant that some people are using (possibly even teaching) PO2 to mean Percentage O2, others have heard of PPO2 but not PO2.

Lets have a poll

 

[Iain3]

I use PPO2 for Partial Pressure and FO2 for Fraction, keep things clear.

 

[42]

i thought it was a shortened version of PPO2. bit difficult to really get them confused though, as PPO2 are likely to be very small numbers and percentages are pretty high numbers. If i said my mix was 1.3, you wouldn't think i'm diving a mix with only 1.3% O2 in it.

 

[42]

PO2 - definition of PO2 in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia.

 

[Okeanos]

I use PPO2 for Partial Pressure and FO2 for Fraction, keep things clear.

Best way to do it IMHO. FO2 is described as a % and not a fraction i.e. decimal.

 

[Two Hats]

Well, reading the medical dictionary linky, it appears that PO2 is Partial Pressure of O2.

Its been a long time since I have done any of the working out (teaching DM physics) but I don't recall ever seeing it written as PO2, only ever as PPO2

 

[davemanroe]

As I just posted in the other thread, the BSAC terminology used in the Nitrox Workshop is PO2 for partial pressure, and FO2 for fraction of O2 (FO2 of Nitrox 36 would be 0.36). i.e. PO2 = FO2 x Absolute Pressure.

 

[Two Hats]

I use PPO2 for Partial Pressure and FO2 for Fraction, keep things clear.

+1

 

[dynarob]

Best way to do it IMHO. FO2 is described as a % and not a fraction i.e. decimal.

It makes life easier if you keep FO2 as a 'fraction', that is what you use in calculations.

eg to find PO2 of air at 20m

FO2 of air is 0.21, P at 20m is 3 bar so...
PO2 (or PPO2?? ) = 0.21 * 3
= 0.63

 

[RichW]

I spent a long time looking at this a while back to see if there was a standard or official SI nomenclature. It seems that pO2 and ppO2 are used interchangeably for partial pressure, with no real debate on whether one is right or not. I try to use one term consistently when working to avoid any potential confusion.

I have NEVER seen PO2 used to express the fraction or percentage, and would advise against doing so. FO2 is for the fraction.

Rich

 

[NotDeadYet]

I've only ever seen PO2 taken to mean partial pressure. Proportion of O2 in a gas has always ever been FO2 or occasionally %O2 on instruments like analysers. AFAIK that's pretty much always been the standard format in technical diving that I can remember (since 1993). Exhibit A, a signed t-shirt from Dick Rutkowski from 1994 with both "FO2" and "PO2" on the logo. He more or less invented mainstream nitrox diving so I would think he'd know.

 

[nigelH]

PO2 means PPO2 but with the added subtext that you don't know what your talking about so you can be safely ignored.

Alternatively maybe you're really clever but just can't tpye.

PS: in solution and in a tissue it is no longer a 'partial pressure' but a 'tension'. HTH

 

[Paul Oliver]

Think the BSAC manuals used to say PPO2 but changed this to PO2 a few years ago.

I could have a look and check but its too trivial to bother with

 

[dynarob]

PO2 means PPO2 but with the added subtext that you don't know what your talking about so you can be safely ignored.

Alternatively maybe you're really clever but just can't tpye.

Who says which is right? Rich Walker says he can't find any standard. A quick straw poll of several (mostly respected) diving books/web sites* this morning reveals that PO2 is used more commonly than PPO2.

How worried should we be for the 6 people (so far) who think it means percentage of oxygen.

*RBW
Tom Mounts Tech Diving Encyclopedia
Understanding Rebreathers
DIR - The Fundamentals of Better Diving
Deco for Divers
Deep Diving
Tech Diving from the Bottom Up
TDI Nitrox thru Trimix
IANTD Nitrox thru Trimix
DAN Dive Medical FAQ

 

[SeaStar]

TBH - I think it shows their is no standard and so everyone is right.
What is important is you understand and remember what you were taught, and if you aren't sure, and your calculations might affect your dive then ask someone whose judgement you trust.

 

[toptribefan]

...then ask someone whose judgement you trust.

we DEFINITELY dont dive with the same group!!

 

[Divingminxsy]

Who says which is right? Rich Walker says he can't find any standard. A quick straw poll of several (mostly respected) diving books/web sites* this morning reveals that PO2 is used more commonly than PPO2.

How worried should we be for the 6 people (so far) who think it means percentage of oxygen.

Just make sure you use PO2 to mean partial pressure not % of oxygen or that bereaver will be living up to its nickname ! :frown::kiss2:

 

[63322]

probably not relevant, just for fun. partial pressure of oxygen abbreviated to PaO2 or PO2 is often used in medicine/physiology to describe oxygen dissolved in a fluid (i.e. blood).

 

[19696]

Hmmm - I do find it mildly amusing to have a poll to prove me wrong - I've been in Congress House this morning, and found this much more interesting than Fit Notes

I've been looking in all the diving books i have, and notice one thing that is common in every formula that is produced. No matter what symbols are used within the formula, there is a little code at the end of it.

P, I have noticed is used to denote, in various different formulae, Pressure at ambient, Pressure in BAR/ata, Partial pressure, Absolute pressure and a whole host of others. Never percentage. So - I seem to be wrong. I will tell myself off, punish myself severly and stand in the corner The OP seemed particularly concerned that I might be actually teaching it wrongly. To be honest - when i teach this stuff, I have the formulae written down, and the little key's with it, so I don't think i have ever taught that, as it wouldn't be that way in the materials the students have.

However, In normal circumstances, if I am referring to Partial Pressure of Oxygen, then it is always, for me, PPO2.

So - the poll is wrong

 

[Mark Powell]

I spent a long time looking at this a while back to see if there was a standard or official SI nomenclature. It seems that pO2 and ppO2 are used interchangeably for partial pressure, with no real debate on whether one is right or not. I try to use one term consistently when working to avoid any potential confusion.

I have NEVER seen PO2 used to express the fraction or percentage, and would advise against doing so. FO2 is for the fraction.

Rich

What he said.

I have seen PO2 and PPO2 used interchangeably to mean partial pressure of O2 but don't remember ever having seen it used to mean percentage of O2.