What does the future hold for rebreathers?

[SoggyFox]

Originally Posted by Mark Chase

But what if your at 20m? And your PP02 is 1.3 but your breathing the gas and motabalising the o2. Then you ascend the PP02 drops quickly and the unit failes to inject more 02 to compenaste, so you pass out and drown.

C02 issues causing hyperventilation and again unconciousness?

High PP02 issues causing 02 tox?

None of thease situations are unmanagable but they take far more care and dicipline than is required for the same dive on OC.

No some very experianced CCR divers have died in less than 20m of water. This is no doubt due to not taking the dive seriously because its just ashallow bimble.

There is no such thing as a bimble dive on a CCR.

I've just spent a weekend diving OC with my club on 20m wrecks, the KISS was left on the side at home and i thought "what the hell. i'll go OC"

It was far easier than CCR, thats for sure, in terms of turn off the brain, fall off boat, watch gauge and puter, surface.

It was not more enjoyable by a long shot.

[Drmike]

Originally Posted by ianfirmin

RB's are NOT more dangerous shallow. .

yes they are. O2 loop levels drop faster in shallows. Therefore risk of death from hypoxia is far higher in shallows/surface (which is why hypoxic death at surface, shallow and even in the swimming pool apears quite often in rb fatality list) This is a risk with any dil but of course especially true if using hypoxic dil. Its impossible to go hypoxic at depth - but its possible to go hypoxic in shallows while ascending, while swimming on surface fighting currents or bouncing around in a swimming pool (the last 3 examples have led to several deaths)

[Drmike]

Originally Posted by SoggyFox

Alternatively playing the Naysmith will help those who are reading this thread to understand more by having you explain your posts in more detail.

fair enough

Its often useful for others who may be hestitant to post questioning such a luminary as yourself.

Cool!
is luminary higher than guru?

[SoggyFox]

Originally Posted by Drmike

Cool!
is luminary higher than guru?

think celebrity..........






think Jade Goody.

[Drmike]

Originally Posted by SoggyFox

think celebrity..........






think Jade Goody.

well I do have a small tattoo on my left buttock....

[BJ]

Originally Posted by Drmike

fair enough




Cool!
is luminary higher than guru?

A luminary leads people into trouble while a guru stays put and sends them.

[nigelH]

Originally Posted by Drmike

O2 loop levels drop faster in shallows.

They do?
And there was I thinking they went down at a steady rate due to me consuming the stuff at the same rate regardless of depth.

[ianfirmin]

Originally Posted by Drmike

yes they are. O2 loop levels drop faster in shallows. Therefore risk of death from hypoxia is far higher in shallows/surface (which is why hypoxic death at surface, shallow and even in the swimming pool apears quite often in rb fatality list) This is a risk with any dil but of course especially true if using hypoxic dil. Its impossible to go hypoxic at depth - but its possible to go hypoxic in shallows while ascending, while swimming on surface fighting currents or bouncing around in a swimming pool (the last 3 examples have led to several deaths)

I'm as well aware of this as you are. For a given PPO2 there are more moles (molecules of O2) in the loop at higher pressure. I alluded to this in the original question. But instead of supplying a reasonable answer you wanted to point out my supposed ignorance. Is this the attitude of someone who wants to enlighten people?

As Mr. Soggy says, many people will have questions. Some of them will be silly. I can be quite an expert at silly questions myself but I have a thick skin.

ATB
Ian

[NotDeadYet]

Originally Posted by nigelH

They do?
And there was I thinking they went down at a steady rate due to me consuming the stuff at the same rate regardless of depth.

I think you know what he means, Nigel. Or at least you should. Small depth change, big PO2 change, basic physics.

[Drmike]

Originally Posted by nigelH

They do?

yes

because im not refering to:

And there was I thinking they went down at a steady rate due to me consuming the stuff at the same rate regardless of depth.

Im refering to rate of change of loop ppo2 increases the shallow you get.

If your bouncing around in a swimming pool (as in changing depth) or in shallows (reef diving changing depth) or generally ascending - the rate of change of loop volume and therefore ppo2 change in the loop is higher than it is deeper (higher the shallower you get). If you have a blocked orifice, turned off o2 tank, unit switched off or any other cause of lack of o2 injection AND you are not aware (for what ever reason) you can go hypoxic if your shallow enough. Add a hypoxic dil into the mix and that can happen even faster.

Deep its almost impossible to go hypoxic because the loop volume would alert you long before you went hypoxic - thats why its safer deeper

A while back (cos im an ass) I ended up on the surface with a loop ppo2 of 0.4 and due to a series of silly ass mistakes there was no O2 injection. In the time it took from surfacing to getting on the boat (struggling, pulling myself along the trail line) my loop ppo2 went from 0.4 to 0.09*! Not good. The same time spent at depth with no o2 injection would have meant an insignificant (from a risk of hypoxia viewpoint) drop in loop ppo2 that would have likely been noticeable anyway due to loop volume reduction.

*observed once i managed to actually look at my handsets once on the boat