p.p. calculations.

[dreammermaid]

I received this email and am trying to calculate which dive profiles he means. Any help appreciated.thanks

Hello there.
A good friend send me your e-mail, with your questions about diving after the bends.
I was personally involve in an accident about 4 years ago, phase II of DCS, after treatment 6 rides in the chamber, i was discharge from medical treatment, treated by the military (excellent treatment i should said). i got back to diving in 3 weeks (yes, i know...) at first just in a pool on pure O2, for about 2 weeks, until i felt secure and (bore), begun doing shallow reef dives on 80%, very shy at first, i keep on playing with PP. of 1.6 at various depth for small intervals of time, them slowly increasing the level of complexity on more demanding dives.

[turbanator]

Originally Posted by dreammermaid

I received this email and am trying to calculate which dive profiles he means. Any help appreciated.thanks

Hello there.
A good friend send me your e-mail, with your questions about diving after the bends.
I was personally involve in an accident about 4 years ago, phase II of DCS, after treatment 6 rides in the chamber, i was discharge from medical treatment, treated by the military (excellent treatment i should said). i got back to diving in 3 weeks (yes, i know...) at first just in a pool on pure O2, for about 2 weeks, until i felt secure and (bore), begun doing shallow reef dives on 80%, very shy at first, i keep on playing with PP. of 1.6 at various depth for small intervals of time, them slowly increasing the level of complexity on more demanding dives.

Well current thinking is that if you are using an RB (fixed PO2), then you would stay well clear of 1.6.
Even on OC, I'd not use 1.6 for the 'working' part of the dive.

hth
Paul

[dreammermaid]

i've written back to ask but haven't gotten a reply. He says its conservative but is 1.6? Here's a bit of additional info from another mail

The P.P was most of the time at 1.6, and i usually try to keep it on the 30 min. interval.
However, i think the key is on avoid loading your body at first, i also use a lot of heliox when i was not in O2.

[Lazlo]

The calculation for Maximum Operating Depth (assuming max 1.6ata for PPO2) is:

MOD = (16 / F02) - 10

where F02 is the fraction of O2 in the mix e.g. 0.21 for Air, or 1.0 for pure O2.

If you work on 1.4 as your max PPO2 then the calculation becomes

MOD = (14 / F02) - 10

and so on.

So plugging in 80% O2 on a 1.6 gives 10m.

As the turbaned one says though - 1.4 is considered safer for the working part of the dive.

That covers O2 CNS toxicity. There are a few ways to calculate oxygen pulmonary exposure as well, but you need tables or a PC for that.

hth

[Lazlo]

Originally Posted by dreammermaid

i also use a lot of heliox when i was not in O2.

Heliox I know nothing about. The above calc is for nitrox only.

[Finless]

The big problem is that no one knows when a reaction to diving with high a ppO2 will occur. I have occasionally dived on a ppO2 of 1.6 even slightly more once - for a whole dive. These were my only dive of the weekend and not in a sequence of repetitive dives.

I don't think anyone can answer your/their question because there is no definitive answer.

The only thing I would say is that use of an FFM would be a good thing as drowning as a result of a convulsion can be taken out of the equation.

[turbanator]

Originally Posted by Lazlo

Heliox I know nothing about. The above calc is for nitrox only.

Lazlo's calc's hold true for Heliox, but you would need to use heliox deco tables, rather than use an EAD on an air table.

[dreammermaid]

I guess I'll try to get back to him. Also how do you dive 80% 02? For the 100% in the pool I was going to try to borrow a DAN surface unit but for 80% I know I need specially o2 cleanes equiptment which I am not qualified for. He's doing great tho, makes deep dives all the time and his case of bends was really severe. An inspiration to me as I have not decided to hang up my fins yet.......

[jb2cool]

just need cylinder and regs oxygen clean. DIR divers regularly use rich mixes like 50% and 100% O2

[dublinbay]

Heliox, 80% ,O2, deep dives.............. And he/she(you) are asking for what exactly? How to calculate CNS/UPTD loadings, run times? Anyone who dives He should know this shit.