| It's in the way the gas is added and personally I find it a bit counter intuitive.
Active is a constant flow through an oriface, like a Drager.
Passive is adding, usually automatically as the counter lung compresses, like a halcyon does.
Passive is a bit more complicated, but has some advantages in that it's harder to 'out-breathe' the mix, i.e. lower the fo2 too far.
The variation of the breathing mix is a lot lower.
hth
Paul
__________________ Baldrick: I did C.
Blackadder: Let's have it then.
Baldrick: "Big blue wobbly thing that mermaids live in." C. Aquanauts
Ocean-Explorers |