has a lower narcotic level than compressed air, > is this good for deep dives ?
No Bonzo, no, Nitrox is only good for semi-shallow dives to 40m or less.
Under higher partial pressure Oxygen becomes toxic. To find out more read the O2-Tox-Page.
> can I do this too and use my normal Regulator for Nitrox or pure Oxygen ?
No Bonzo, no, don't be so mad to use your normal Air Valves or Air Regulators for anything else than Air.
> to do good buoyancy fine control without hands.
> So how can I use a Rebreather when doing UW-filming work ?
Don't worry, your first step before buying a Rebreather is getting qualified to dive one. So ask the training facilities on which type of Rebreather they can teach you to do good buoyancy fine control without hands. I found out how to do a real good buoyancy fine control without using my hands when diving with LAR5, Atlantis-1/Dolphin, FGT-1 and IDA-71 and I engineered a gadget that allows fully hand-free buoyancy fine control on CCR-rebreathers like the Buddy-Inspiration.
> and then dive with a Solenoid Setpoint of 1.6bar ppO2 ?
Be careful, if it works fine with new Sensors that's no Garantee that it will still work after they degraded to old ones. As sensors age, the output voltage will plateau at some point, so you will get too low readings on values above the calibration point. Worst case all 3 sensors have the same age, display exactly the same wrong result (this is pretty unlikely) and let the ppO2 raise to a much higher value than you intended.
1.6bar is quite high Oxygen-partial pressure if constant for the entire dive, it will limit the time of your dive. I would suggest to dive a ppO2-setpoint of 1.0bar (Caution: think about EAD, I prefer long shallow dives) and check on pure Oxygen in shallow water (or in the pressure-pot) if the reading is still linear above your setpoint, e.g. you should read ~1.6bar ppO2 in 6m.
No Bonzo, no !
#1 You shall only do what you are certified for.
#2 Your Diluent is your Bailout too, it has to be breathable, that means at least 10% O2.
#3 Think about Dekompression and only do the dives your bailout logistic allows.
No, don't worry. Ok, you need to get qualified for it, but it is not much more expensive than running your CCR as Nitrox-Rebreather. Even in Germany you can afford to dive Heliox if you ride a CCR, a fill of a 50 liter 200 bar storage tank with Heliox16 costs about 200Euro here and should last for more than 20 dives.
Diving with Heliox is not a black magic at all, it's a responsible way to handle the problem of nitrogen-narcosis, but you need to know how to handle Helium Decompression-Tables and be wise enouth not to reach out for HPNS.
> I imagine because of the heat generated in the rebreather-loop.
Hi, you discovered the termal capacity bug that is still found in some books
Helium has a significant higher termal capacity per mass, but you breath per Liter,
at given pressure that means per Mol (1mol=22,4bar*liter), and so it has a lower termal capacity.
Cp (He)=20,9 Joule/(mol*Kelvin)
Cp (N2)=29,0 Joule/(mol*Kelvin)
Cp (O2)=29,3 Joule/(mol*Kelvin)
In units that fit for Divers:
Cp (He)=0,933 Watt*sec/(bar*Liter*Kelvin)
Cp (N2)=1,295 Watt*sec/(bar*Liter*Kelvin)
Cp (O2)=1,308 Watt*sec/(bar*Liter*Kelvin)
> fascinated with the idea of re-breathers.
> I am thinking of investing in one but would like some advice before I take the plunge.
There is more to competent Rebreather diving than simply knowing information. Will the diver meticulously attend to every detail in maintaining and prepping their unit? Do they have reasonable mechanical sense or do they tend to overtighten, undertighten, misalign and otherwise be mechanically inept? Will they pay attention to every nuance of the functioning of their unit while diving? Will they be totally aware of what they are doing and which valve they are using when they do a gas switch? How will they react psychologically if things go wrong? Do they tend to daydream or become one track minded when engrossed in a task?
Such things for the most part either can't be taught or are outside the scope of existing training but are very much a part of successful rebreather diving.
(Above cited from a text which was written by Walter Starck, my own English is too poor.)
You should make up your mind what you want to do with the Rebreather, in order to find out which one is the one you need. There is no
I think the best Idea is to find a Group in your area which does the type of diving you want to do, so that you learn from and dive with them.
By principle the way to Rebreather-Diving is (for example (http://pan-tec.de)):
o OWD/* +30dives
o Nitrox-Diver (including AOW/**)
o Rebreather Diver (Type specific) + 20 Rebreather-hours
o advanced Rebreather Diver (Type specific)
>it has two tanks and the capability of set the supply flow's at anytime.
>
>My idea is to set a too low pressure on the Oxygen to restrict the flow/min,
>more you go deep more the flow is restricted......
Hmm, that thought contains a bug, and if that is fixed I think that the resulting concept would be a quite demanding piece of engineer work.
Look at what Premix Active-Flow SCR's do: they supply an Oxygen Flow that is sufficient even in cases of harder work.
EAN60 <> O2: 3,48 barl/min N2: 2,32 barl/min EAN50 <> O2: 3,65 barl/min N2: 3,65 barl/min EAN40 <> O2: 4,16 barl/min N2: 6,24 barl/min EAN32 <> O2: 4,992barl/min N2: 10,608barl/minIf you wonder why the O2 Mass-Flow is raising with the possible depth, the answer is easy: besides the accepted tolerances (in fsO2 and Gas-Flow), those Turtles are using the same Supply-Gas from the Surface to the MOD, what means they need to be designed for a sufficient ppO2 at the Surface.
For Your Idea it should work with a constant O2-Flow and a Dil.-Flow that is increasing with the Depth.
Sure, the Dil. should be beathable and so also means a supply with some of Oxygen, so You see why there is no such Rebreather on the Market jet: designing an ECCR or a passive-flow SCR looks a lot cheaper.
Rebreather-Index