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Discussion Starter · #1 ·
I received this email and am trying to calculate which dive profiles he means. Any help appreciated.thanks :shade:

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.
 

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

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
 

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Discussion Starter · #3 ·
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.
 

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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
 

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dreammermaid said:
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.
 

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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.
 

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Lazlo said:
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.
 

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Discussion Starter · #8 ·
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.......
 

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

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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.
 

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dublinbay said:
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.
I didn't get the impression the "emailer" was asking for anything. As far as doing pool dives on a DAN unit *shudders* I wouldn't for various reasons.

If you have the appropriate training you can use O2 percentages as high as you like. If you have the training, you'll know where to get it and how to use it.

Anyway, good luck to your friend, I hope he gets back to normal as soon as medically possible. :)
 

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Discussion Starter · #12 · (Edited)
dublinbay said:
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.
I'm not really a tech diver. I got DCS II and after many months of searching found someone who had the bends worse than I did who returned to deep diving. He sent me the email as what worked for him. So I am just trying to figure out what it means in terms of dive profile. Sorry if I come across as ignorant...l..
Ok no DAN unit in the pool, it was just a thought but maybe a bad one?
 

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dreammermaid said:
I'm not really a tech diver. I got DCS II and after many months of searching found someone who had the bends worse than I did who returned to deep diving. He sent me the email as what worked for him. So I am just trying to figure out what it means in terms of dive profile. Sorry if I come across as ignorant...l..
Ok no DAN unit in the pool, it was just a thought but maybe a bad one?
There seem to be a number of issues:-

Do you know (from the diving doctor) what caused your DCI + what were their recommendations on your continuing to dive.

Nitrox diving sounds like a good course for you to take BUT it won't help you with "deep" diving.

It sounds like, to me, you need an advanced nitrox course where you use high O2 mixes for accelerated deco - except you will be using them to build in added safety margins on the safety stops.

If I am reading this correctly you are looking for a magic get out clause of avoiding another DCI - sadly there isn't one. Obviously there are things to help prevent such problems but if you are at risk due to some medical problem or .........

The sort of advice you are seeking is very specific and is really the sort of thing that is learnt during the appropriate course.
 
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dreammermaid said:
I got DCS II and after many months of searching found someone who had the bends worse than I did who returned to deep diving.
Ah yes - good luck to you as well. :)

It's generally not a good idea to muck about with O2. There are loads of issues for which you require training. If you've done a nitrox course you'll know about some of them already.

Your friend sounds like he was basically trying to use as little N2 in his breathing gases as possible - to reduce the risk of N2 bubbles by raising the proportion of O2 and/or He. But again, without training in the use of these gases you run other risks just as great as DCS.

If I were you I would seek out a proper diving doctor to advise you. That's the trouble with the internet - you'll get a thousand answers and you can't really trust any of them. :) If you were in the UK I could give you some references, but California ... no idea. You could try http://www.e-med.co.uk/ though. He will usually respond within a day or so, and it's free!
 

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Discussion Starter · #15 ·
thanks

yes of course the correct training is necessary. I am aware of the risks of returning to diving but I still would like to try. Certainly staying out of the water is the safest option. It was definitely an 'earned' hit . dragged down too deep, popped up too fast. I'll make sure to have the correct supervision and thanks for all or your posts of advice. Much appreciated.
 

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dreammermaid said:
yes of course the correct training is necessary. I am aware of the risks of returning to diving but I still would like to try. Certainly staying out of the water is the safest option. It was definitely an 'earned' hit . dragged down too deep, popped up too fast. I'll make sure to have the correct supervision and thanks for all or your posts of advice. Much appreciated.
Hi Dream Mermaid.

I would really recommend doing a simple Nitrox course. Nitrox will make your diving safer, and is dead easy to use. In fact it's so easy there are some courses out there which don't even include any dives - it's just a few hours of theory.

The course will explain all the basic questions you have here. It will explain about ppO2's and 1.4 and 1.6 and how to breathe 80%, and the advantages but also the disadvantages of doing so.

Cheers,
Janos
 

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dreammermaid said:
yes of course the correct training is necessary. I am aware of the risks of returning to diving but I still would like to try. Certainly staying out of the water is the safest option. It was definitely an 'earned' hit . dragged down too deep, popped up too fast. I'll make sure to have the correct supervision and thanks for all or your posts of advice. Much appreciated.
In view of the reasons for your DCI being so obvious then I shouldn't worry. Just get in the water and take it nice and slow. Being dragged down sounds totally out of your control and "popping up quickly" should, ordinarily, be within your control.

FWIW, I nearly killed myself on one dive due to my own stupidity and lack of preparation. I have learned from my mistake, have become a MUCH better diver. I'm sure you'll find the same about yourself when you get back in.
 

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Janos said:
Hi Dream Mermaid.

I would really recommend doing a simple Nitrox course. Nitrox will make your diving safer, and is dead easy to use. In fact it's so easy there are some courses out there which don't even include any dives - it's just a few hours of theory.

The course will explain all the basic questions you have here. It will explain about ppO2's and 1.4 and 1.6 and how to breathe 80%, and the advantages but also the disadvantages of doing so.

Cheers,
Janos
Ok I am a bit confused, Dream Mermaid says she isn't a tech diver but her website lists a whole load of stuff including:

Gas Blender, NITROX, TecRec Trimix Blender

and the website says she is currently instructing, have I just misunderstood somewhere. :confused:




 

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Fiona said:
Ok I am a bit confused, Dream Mermaid says she isn't a tech diver but her website lists a whole load of stuff including:

Gas Blender, NITROX, TecRec Trimix Blender

and the website says she is currently instructing, have I just misunderstood somewhere. :confused:




Where did you get the website address from?
 
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