Gas Density Calculator

**Steve** · 22nd August 2005, 04:13

I used to have a handy bit of software that I could plug in the mix and the depth and it would tell met the equivalent air density depth. I have lost it and would like another. Anyone?

decoweenie · 22nd August 2005, 05:01

Quote: (Originally Posted by Steve)

Anyone?

You mean computing the EAD of trimix for different depths ?

If you are using the Palm, you have options of using certain decompression and/or blending programs to extract that.

Or send me a bottle of Australian Shiraz and I will whip one on the Palm for you...

If you don't want portability, Excel is easy to do.

Underwaterbear · 22nd August 2005, 05:03

Is it not just a simple calc based on ratios of atomic weights?
Try this xls sheet (hmm lets see if I can attach it somehow)

wizbang · 22nd August 2005, 05:54

Steve GMP has it at the end of the program.
Density O2 N2 and He and depth.
hope that helps.Wiz

Bear · 22nd August 2005, 10:01

Steve, ya big blouse.....

That wouldn't have been than nice bit of coding that i sent you ages ago that also included remixing gases, trimix fills etc? Check your email as there is something sitting in it for you!!

Cheers

Tim Cashman · 26th August 2005, 15:07

Its a straight forward case of gas % x gas density at STP x pressure at depth = density at depth
Density of individual gases in kgs/m3 at STP is
O2 1.429
N2 1.250
He 0.179
CO2 1.977

eg density of air at 40m (O2 + N2)
(1.429 x 21% x 5ata) + (1.250 x 79% x 5ata) = 6.438 kgs/m3

eg 2 density of trimix 13/60 at 100m (O2 + He + N2)
(1.429 x 13% x 11ata) + ( 0.179 x 60% x 11ata) + ( 1.250 x 27% x 11ata) = 6.937 kgs/m3

These calcs are not precise but give an indication of whats afoot.
I think its important to at least be aware of this stuff, as breathing too dense a mix at depth can easily exceed the equivalent work of breathing of air at 40m and predispose CO2 accumulation. Gas selection is not just about ppO2 and narcosis.

The gas flow is most restricted within the bronchioles and finer passages of the lungs so don't waste time on equipment specs and tripe about rated depths of your Rebreather etc.
The lungs is the weakest link in the chain.
Breathe all the way in and all the way out, to get as much of that nasty CO2 out of your lungs on the exhale as possible.
Use plenty of helium to make the work of breathing as easy as possible.

I've got a spreadsheet which does all this simply but am too stupid to know how to attach it.
TC

22nd August 2005, 04:13	#1 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,117	Gas Density Calculator I used to have a handy bit of software that I could plug in the mix and the depth and it would tell met the equivalent air density depth. I have lost it and would like another. Anyone? __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
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22nd August 2005, 05:01	#2 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Quote: (Originally Posted by Steve) Anyone? You mean computing the EAD of trimix for different depths ? If you are using the Palm, you have options of using certain decompression and/or blending programs to extract that. Or send me a bottle of Australian Shiraz and I will whip one on the Palm for you... If you don't want portability, Excel is easy to do. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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22nd August 2005, 05:54	#4 (permalink)
wizbang WEB MERMEN Current Rebreather/s: Inspiration Classic Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Vision Evolution Prism Topaz Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Perth Australia Posts: 386	Steve GMP has it at the end of the program. Density O2 N2 and He and depth. hope that helps.Wiz
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22nd August 2005, 10:01	#5 (permalink)
Bear Smelling Dairy Air Current Rebreather/s: Other CCR Dolphin Home Build Not Bought Yet Other Rebreather/s: Other CCR Dolphin Home Build Not Bought Yet Join Date: Apr 2005 Location: Melbourne, Australia Posts: 101	Steve, ya big blouse..... That wouldn't have been than nice bit of coding that i sent you ages ago that also included remixing gases, trimix fills etc? Check your email as there is something sitting in it for you!! Cheers __________________ http://www.victech.org VICTECH.ORG: A web resource for Technical Divers in Victoria
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26th August 2005, 15:07	#6 (permalink)
Tim Cashman New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Aug 2005 Location: Wales Posts: 55	Its a straight forward case of gas % x gas density at STP x pressure at depth = density at depth Density of individual gases in kgs/m3 at STP is O2 1.429 N2 1.250 He 0.179 CO2 1.977 eg density of air at 40m (O2 + N2) (1.429 x 21% x 5ata) + (1.250 x 79% x 5ata) = 6.438 kgs/m3 eg 2 density of trimix 13/60 at 100m (O2 + He + N2) (1.429 x 13% x 11ata) + ( 0.179 x 60% x 11ata) + ( 1.250 x 27% x 11ata) = 6.937 kgs/m3 These calcs are not precise but give an indication of whats afoot. I think its important to at least be aware of this stuff, as breathing too dense a mix at depth can easily exceed the equivalent work of breathing of air at 40m and predispose CO2 accumulation. Gas selection is not just about ppO2 and narcosis. The gas flow is most restricted within the bronchioles and finer passages of the lungs so don't waste time on equipment specs and tripe about rated depths of your Rebreather etc. The lungs is the weakest link in the chain. Breathe all the way in and all the way out, to get as much of that nasty CO2 out of your lungs on the exhale as possible. Use plenty of helium to make the work of breathing as easy as possible. I've got a spreadsheet which does all this simply but am too stupid to know how to attach it. TC __________________ Iechyd da
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