Forget "IDEAL" & "GET REAL"!!

[DeepSeaDan]

Hey all you consumers of compressed gases:

Was just rootin' around the web & came upon a facinating bit of physics. Now instead of me trying to wax phdish, just go to these links:

http://www.diveinstruct.org.uk/vanderwaals.html

http://www.combro.co.uk/nigelh/diver/vdw.html


& read up. I'd be real interested to hear from our Dr.'s as to their take on all of this & what it means for us high-pressure inhalers...

Regards,
D.S.D.

 

[jbd]

Hey all you consumers of compressed gases:

Was just rootin' around the web & came upon a facinating bit of physics. Now instead of me trying to wax phdish, just go to these links:

http://www.diveinstruct.org.uk/vanderwaals.html

http://www.combro.co.uk/nigelh/diver/vdw.html


& read up. I'd be real interested to hear from our Dr.'s as to their take on all of this & what it means for us high-pressure inhalers...

Regards,
D.S.D.

I think all that math means there's less gas in the tanks than I thought there was. :06: Maybe the LDS's should cut the price of the fills

 

[Don Burke]

This is not news.

Different fudge factors are used for different gasses. They have been for years.

 

[DeepSeaDan]

This is not news.

Different fudge factors are used for different gasses. They have been for years.

Hey Don,

Agreed, but if Van Der Waal is more precise & could be made useable to the masses, why do we stick with Dalton? Why not get a more accurate amount when blending by using that British chaps nifty blender program?

Is it time to re-write part of the diving physics chapters of our textbooks?

 

[String]

Well known fact taught even in basic training for new divers here.

There was a great web page (UK based) with a calculator script as well as the different graphs for different gases on it but i cant find it now.

 

[RedCash02]

Originally Posted by jbd
I think all that math means there's less gas in the tanks than I thought there was. Maybe the LDS's should cut the price of the fills

Van der Waal's Law can also mean that you could get getting more gas than you actually thought too. Or, maybe, gases really do have voodoo and that's why we're paying so much

 

[DeepSeaDan]

Van der Waal's Law can also mean that you could get getting more gas than you actually thought too. Or, maybe, gases really do have voodoo and that's why we're paying so much

Rumour has it the amount of available He. stocks is dwindiling fast...could mean a switch to Hydrogen...no smoking, please.

D.S.D.

 

[Don Burke]

Agreed, but if Van Der Waal is more precise & could be made useable to the masses, why do we stick with Dalton?

Dalton's Law is not one of the gas laws in question here. I believe you are thinking of Boyles and Charles.

Why not get a more accurate amount when blending by using that British chaps nifty blender program?

It is not more accurate. A computer program that applies correction factors is no more accurate than a human who applies correction factors.QUOTE=DeepSeaDan]Is it time to re-write part of the diving physics chapters of our textbooks?[/QUOTE]No. The laws have not changed. This has been known at least since carbon dioxide was first compressed into a liquid and probably well before that.

It was not much of an issue for divers until pressures went higher and gas mixes become more popular.

In fact, most nitrox mixes track closer to the ideal gas than air does.

 

[Don Burke]

Rumour has it the amount of available He. stocks is dwindiling fast...could mean a switch to Hydrogen...no smoking, please.

It would involve an interesting gas switching scheme to stay below the LEL and above the UEL. Since the narcosis advantage over nitrogen is minor, I doubt it will catch on.

I suspect air reduction will become a viable source for helium when the natural gas wells become depleted.

 

[String]

Helium depletion isnt a rumour - its a fact. The places its mined from (yes mined) are drying up, prices have already risen dramatically in the last decade or so.

I agree with Don Burke here in that reduction in the quantity of gas used could be the focus in the future as opposed to new gases. Id go one step further and suggest SCRs and CCRs used more and more for technical dives which would be done on open circuit currently.