I was having fun discussing various dive technologies with a buddy the other day and I got to thinking about this idea, wondered if you rebreather guys had ever heard of such a thing, or why it wouldn't work.
The idea is basically a one-breath rebreather. Based on the fact that a typical exhaled breath still contains plenty of O2, certainly enough for one more breath, I imagine a "rebreather" with a single nitrox cylinder, a double hose, semi-automatic two-way valves on both intake and exhaust, and a counterlung.
Every two breaths would constitute one cycle:
In other words, rebreathe just one breath, then take a fresh hit of nitrox.
Wouldn't have much advantage over plain open circuit, just an increase in gas efficiency. But seems like that increase could potentially be significant. Buoyancy would be kinda wonky, as it would vary every other breath. But it would also be very simple - no sorb, no diluent, etc., and seems like it could also be reasonably compact.
Of course the above procedure is simplified and there would need to be lots of checks and balances to make sure, for example, that the counterlung gets completely flushed each time, that the valve doesn't get stuck so the diver is unwittingly rebreathing one breath over and over, etc. One obvious problem would be if the diver descended much between the first and second breaths, there wouldn't be sufficient volume in the counterlung for another breath - going up would be the opposite, but seems like that could be solved fairly simply with an OPV.
But I was wondering if anything like this has ever been tried, and/or why it couldn't possibly work.
The idea is basically a one-breath rebreather. Based on the fact that a typical exhaled breath still contains plenty of O2, certainly enough for one more breath, I imagine a "rebreather" with a single nitrox cylinder, a double hose, semi-automatic two-way valves on both intake and exhaust, and a counterlung.
Every two breaths would constitute one cycle:
1) Upon initial inhalation, intake from nitrox cylinder.
2) Upon initial exhalation, exhaust to counterlung.
3) Upon second inhalation, intake from counterlung.
4) Upon second exhalation, exhaust to water.
2) Upon initial exhalation, exhaust to counterlung.
3) Upon second inhalation, intake from counterlung.
4) Upon second exhalation, exhaust to water.
In other words, rebreathe just one breath, then take a fresh hit of nitrox.
Wouldn't have much advantage over plain open circuit, just an increase in gas efficiency. But seems like that increase could potentially be significant. Buoyancy would be kinda wonky, as it would vary every other breath. But it would also be very simple - no sorb, no diluent, etc., and seems like it could also be reasonably compact.
Of course the above procedure is simplified and there would need to be lots of checks and balances to make sure, for example, that the counterlung gets completely flushed each time, that the valve doesn't get stuck so the diver is unwittingly rebreathing one breath over and over, etc. One obvious problem would be if the diver descended much between the first and second breaths, there wouldn't be sufficient volume in the counterlung for another breath - going up would be the opposite, but seems like that could be solved fairly simply with an OPV.
But I was wondering if anything like this has ever been tried, and/or why it couldn't possibly work.