Deep dive gas mixer?

[DaleC]

I think that as soon as you begin adding bailout to such a unit you lose the main advantage it would have over traditional OC ie. compact size, especially considering how big the bailout would have to be. The "units" potential would be for calculating extended dives based on deco with 50/50 & O2 so the bailout would have to be contingent on doing that same deco on air (or whatever nitrox mix did not violate the intended MOD). You could dive conservatively so that bailout would cover deco but then you would really under-utilize the units capacity.

For the same bailout with OC you should have doubles which you can isolate, a bottle of 50/50 you could move up to and use and a bottle of O2 you could also use, but in stages. Your deco strategy would still be followed except for the one component that failed. With the "unit" you would have to go to either an air deco plan or a straight O2 plan, depending on which part failed.

I hope that makes some sort of sense.

 

[tbone1004]

Frosty, you are carrying three bottles minimum, but if you were mixing all three gasses you would have three radically different sized bottles, or carrying an excessive amount of gas.

For deep diving carrying 12/70/18, you would think be carrying one huge tank of helium, and two smaller tanks of O2 and nitrogen, but the O2 tank for bottom gas, but would then have to make them bigger for your decompression obligations. For OC square profiles there is no advantage of having continuous mixing because the gas switching done is all optimized for the depth you're going to be at. For normal diving, the added cost of such a system would be about the same as a full out rebreather, and the inefficiencies involved of open circuit over closed circuit would make it cost prohibitive.