Gue Vs Tdi

[BigJetDriver]

maybe (sic) this is farm animal stupid, but the word decompression means the release of pressure. In the NDL dive tables gives use to (sic) the term "pressure group" to quantify residule (sic) nitrogen in the blood, they use letters to do this, and maybe this "letter" throws some divers for a loop. What they really mean is you have residule (sic) N2 pressure in your body and you need to take this "pressure group" into account for your next dive.
When planning dives with nitrox , divers plan on using safe partial pressure, and when divers plan decompression dives they plan on higher partial pressures of O2 to LOWER the partial pressure of N2.
Now if this is lost on some, it won't matter what agency you train with . If you have a PHD and dissagree (sic) wih me, then it still won't matter what agency you train with.

If there is a technical diver on SB that can prove this wrong I'll never post here again. If your (sic) a recreational diver with a PHD in something other than diving , (sic) Please keep your opinion to yourself

Despite the terrible spelling, the execrable grammar, and the supremely arrogant attitude, what is quoted above is relatively correct!

 

[cornfed]

Despite the terrible spelling, the execrable grammar, and the supremely arrogant attitude, what is quoted above is relatively correct!

True, but the issue I've been pushing is what drives those pressures he keeps talking about.

 

[WarmWaterDiver]

nobody appreciates a good physics problem these days...QUOTE]

Untrue - but the audiece is selective for such appreciation. First, you have to have participants that actually care about degree of accuracy of the discussion, and second, knowledge and appreciation of algebra as a starting point for examining the relationships. All that's required is for one participant to not buy into this to sow discord - and maybe demonstrate Heisenberg may well have known his stuff.

One can also examine ideal behavior fundamentals for a monatomic gas (modeled imperfectly, but closely, by helium) versus ideal behaviors for diatomic gas molecules (modeled imperfectly by O2 and N2, among others) and get the same proportionalities if I again remeber my physical chemistry and / or advanced thermodynamics correctly. These can be expressed as a multiplier of R, the universal gas constant, and the multiplier changes whether the gas is monatomic, diatomic, etc.

This thread has given me inspiration to change my signature line - the old one was getting a bit stale anyway.

 

[Hank49]

nobody appreciates a good physics problem these days...



so, from basic physical dynamics (good old billiard balls bouncing off the walls of a container) you can arrive at:

P = 2/3 (N/V) (1/2 m <v^2>)

then the equipartition theorem does, in fact, hold:

Ek_x = 1/2 kT
Ek_y = 1/2 kT
Ek_z = 1/2 KT

Ek_tot = 1/2 m <v^2> = 3/2 kT

which leads by substitution to:

P = 2/3 (N/V) (3/2 kT)

which gives us:

PV = NkT

w00t.

for diatomic gases (N2 / O2) you also get for total energy from the equipartition theorem:

E_tot = Ek + rotational + vibrational = 3/2kT + 1/2kT + 1/2kT = 5/2kT

this affects the heat capacity of the gases and makes N2 and O2 at a given temperature contain more energy than He -- or stated otherwise, warming up N2 and O2 to body temperature takes away more energy from the body than He -- which is why He is actually not a cold gas to breathe.

Damn Lamont...I have to know all this stuff to dive now? I guess I'll have to go back to riding dirt bikes and surfing....wait..I'm 50 now...I'm too old..awwwww crap....

 

[lamont]

Damn Lamont...I have to know all this stuff to dive now? I guess I'll have to go back to riding dirt bikes and surfing....wait..I'm 50 now...I'm too old..awwwww crap....

well, if you're okay hanging out at the strokepits with the star wars bar scene and don't want to go downtown, you'll be fine...

all the real players use the equipartition theorem on every dive...

 

[WarmWaterDiver]

Lamont, if I'm ever traveling to the Pacific NW, I'll have to drop you a line to at least meet for coffee - somewhere downtown! I just prefer to remember it as a fucntion of e raised to a power of minus kT divided by R, with the monatomic, diatomic, etc, proportionality out front - more for use in manipulating gas behavior - although as you point out, the Maxwell perspective and quantum approach is equally valid.

This thread should give some folks a different perspective of using one's brain as one's primary dive 'computer' that perhaps they hadn't thought of previously.

And, maybe this thread and its convolutions indicates the sub-forum of"The Science and Physics of Diving" should be resurrected - we're starting to get back to some of the "old" stuff that was in that forum again!

http://www.scubaboard.com/showthread.php?t=97022

 

[lamont]

Lamont, if I'm ever traveling to the Pacific NW, I'll have to drop you a line to at least meet for coffee - somewhere downtown!

definitely. i work and live very close to 'downtown'.

I just prefer to remember it as a fucntion of e raised to a power of minus kT divided by R, with the monatomic, diatomic, etc, proportionality out front - more for use in manipulating gas behavior - although as you point out, the Maxwell perspective and quantum approach is equally valid.

its been too long and i can't find my @#!$@#$ stat mech book, but you're making me seriously jones...

 

[Doc Intrepid]

well, if you're okay hanging out at the strokepits with the star wars bar scene and don't want to go downtown, you'll be fine...

all the real players use the equipartition theorem on every dive...

its been too long and i can't find my @#!$@#$ stat mech book, but you're making me seriously jones...

Lamont, you are a sick man. A very, very sick man.

 

[lamont]

Lamont, you are a sick man. A very, very sick man.

who you calling a man? :martian:

 

[nova]

perhaps they should start a Mensa forum .