Quote: (Originally Posted by Devon Rob)
Has anyone got a good LAYMANS explanation for handling the PO2 drop on SCR by ascent? All the technical explanations are making my head spin
and yes I do know it has to do with the reduced ambient pressure!
something along the lines of, The deeper you go the less oxygen by % in the gas you breath will be needed to sustain life. That is why deep dives on trimix will have an Oxygen percentage below 21%, the normal amount of oxygen in the atmosphere, Many trimix rebreathers (NOT DIR BTW) will provide an optimal mix as you go deeper, reducing the oxygen (and nitrogen) content as you go deeper and adding helium, as you go up those values will be increased and the helium reduced (helium % can be looked at a few ways depending on how the diver chooses/the machine is programed). If the rebreather fails to increase the oxygen on assent then the diver may well find they do NOT have enough oxygen to survive and thus expire. It is a very insidious way of dying. Rebreathers have a few incidious ways of killing a diver.
They sure save money on Helium however!