[Mal Bridgeman]

Originally Posted by Depth-junkie

Depends if you have an ADV (automaic dilutent valve) fitted or not. If you do then it acts baiscly the same as a reg, as soon as it feels negaive pressure against the diaghram it adds in gas. Basicly works the same as sucking on a reg(diaghram sucks in on inale and pushes needle valve and opens up the gas path in turn adding gas)

If no ADV you have to manualy add in the Dil via the counterlung buttons (when you feel negative pressure I.E cant suck in any gas-push the button on the inhale lung)

The use of an ADV basicly gives you one less thing to do, and leaves you hands free for the decent.

As for the PO2 on decent, it obviuosly goes up inline with the added ambeint pressure. But the addition of Dil keeps it within safe levels.

For whatt its worth i switch up to high setpoint (1.3pp02) @ 10m on decent even for deep 90m+ dives as the addition of Dil keeps my PO2 in the 1.00 region on the decent, it also allows me to spike the PO2 above setpoint on the decent to make sure cells are not current ltd (just hold my breath for a few meters and make sure cells reach 1.4-1.5).

So by the time i reach the wreck i am all set to go, and not have to faff about with switching from low to high and current ltd test.





ATB
Gareth

OK so what I am understanding is that with an ADV the descent load on the diver is not a great deal different to an OC diver .... just clear your ears and inflate your wing to compensate for the buoyancy shift.

On the ppO2 front, if you have a ppO2 of 1.3 at 10m how do you get it down by the time you get the wreck? .... Does the automatic addition of diluent keep it down?

Once I have understood this, I am likely to ask questions about what happens on the ascent.

Before I do though, why a pp02 of 1.3? What is the wisdom behind that?

Cheers
Mal