Can you help me learn about: gas management and basic deco therory?

[dsteding]

Memorize and understand Lamont's excellent Rock Bottom page that he's put together. It is linked in his signature line, and there was a recent thread on it.

It will give you more than just rock bottom numbers, it will also give you good first-pass understanding of gas management principles.

I'll second or third Bob's gas management handout, and the battlefield calculation stuff from 5thd-X is good stuff, but it takes a while to work through and truly understand.

 

[TSandM]

Leah, I knew your opening post sounded familiar!

 

[bperrybap]

For gas management, PM NWGratefulDiver for his gas management lecture handout. Also read lamont's paper on Rock Bottom which he links to in his signature line. If that's not enough, go to www.5thD-x.com, click on "learning center", and then on "battle cal" and it will pull up links to several PDFs, among them "Battlefield Calculations", which is a whole set of arithmetical shortcuts for doing gas planning calculations in your head.

Lynne, I've read those papers and several others on weighting,
SAC, and even DIR.
They are quite good and informative.
Being on SB staff, is it possible that you could work with the
authors and get those papers placed in the "Articles" section
of SB.
This seems like the perfect place for these types of papers
yet currently there are not any on these topics and questions
about these topics come up all the time.

Sure would be great if we could simply refer folks to the
[Articles] section of SB instead of having to make them
search for the information embedded within the forums.

I'd even be happy to write some papers for submission to
SB staff for consideration for inclusion in the [Articles] section,
but I'm not sure of the process to make this happen.

--- bill

 

[JasonH20]

I read the battle field article and it's pretty good. I found yet another reason why I like my 130's now...

130CF/3442psi = 3.78 CF/100psi (Tank Factor)
Figure a .75 SCR (surface consumption rate)
.75CF/Min x 5Min = 3.75CF every 5 minutes per atmosphere.
So it works out close enough for 100 psi every 5 minutes per atmosphere. Must be divine intervention.

 

[lamont]

I read the battle field article and it's pretty good. I found yet another reason why I like my 130's now...

130CF/3442psi = 3.78 CF/100psi (Tank Factor)
Figure a .75 SCR (surface consumption rate)
.75CF/Min x 5Min = 3.75CF every 5 minutes per atmosphere.
So it works out close enough for 100 psi every 5 minutes per atmosphere. Must be divine intervention.

Yeah, 100 psi / 10 min / ata for double-130s, 200 psi / 10 min / ata for single 130s, 300 psi / 10 min / ata for single Al80s.

I tend to use 300 psi / 10 min @ 100 fsw for my double-130s which works out to around a .60 SAC rate though. I also found that 500 psi / 10 min was a nice round number to use at 50-60 fsw on my single-130s on DIW dives...

BTW, the link in my sig isn't working today unfortunately because my DNS/web server crashed last night and I'm at work and can't reboot it...

 

[rjack321]

Try here:

http://www.dive-tech.co.uk/links.htm#deco
http://www.decompression.org/maiken/Bubble_Decompression_Strategies.htm
ftp://decompression.org/pub/Baker/Deep Stops.pdf

If you can get through the last one's graphics you're beyond "basic"

 

[lamont]

Try here:

http://www.dive-tech.co.uk/links.htm#deco
http://www.decompression.org/maiken/Bubble_Decompression_Strategies.htm
ftp://decompression.org/pub/Baker/Deep Stops.pdf

If you can get through the last one's graphics you're beyond "basic"

The Gradient Factor stuff is kind of voodoo though and is only half the picture. The other half is that you are keeping free-phase bubble nuclei smaller by doing deep stop and smaller bubbles actually offgas faster because their surface tension is higher, so the pressure inside the smaller bubbles is higher, so the offgassing gradient is higher in smaller bubbles. Its not just about keeping the gradients lower, but its about not growing large bubbles.

 

[rjack321]

Welll I didn't say there was agreement amongst all the info sources Heck the first link has Haldane theory in there!

Its true that the Baker doc isn't the be-all end-all. But it is still beyond basic IMO.

 

[lamont]

Welll I didn't say there was agreement amongst all the info sources Heck the first link has Haldane theory in there!

Its true that the Baker doc isn't the be-all end-all. But it is still beyond basic IMO.

Yeah, it is good to read that one after you've figured out Haldane/Buhlmann theory, but it is good to keep in mind that its sort of a mathematical trick which happens to work to give the correct results. It does illustrate what is going on in the dissolved phase after applying the corrects for free-phase deco theory profiles, though. It isn't wrong, it just isn't the whole explanation behind deep stops.

 

[Pod Diver Radio]

Lots of good info and advice on this thread. I would like to suggest that you subscribe to my podcast POD DIVER RADIO

I produce a weekly podcast on diving and we have quite a back-catalog that might be helpful as well. Each week I interview dive scientists, explorers and educators. I would suggest the following episodes in your quest for knowledge.

http://media.libsyn.com/media/poddiver/RGBM_with_Dr_Bruce_Weinke.mp3 RGBM Decompression Theory

http://media.libsyn.com/media/poddiver/PD049.mp3 Bob Sherwood talks about the GUE DIR-F class.

http://media.libsyn.com/media/poddiver/PD030.mp3 Gas Management