SCR peaking pO2 on descent.

Freef

I was speaking to a diver yesterday who was wondering if they had a fault on their pO2 meter as it went high on descent.

When you are descending on SCR, especially with a low flow rate jet, the following will happen:

If you go off the loop for any time before the descent the loop fO2 will rise as you are not extracting any O2. Left long enough the loop fO2 will rise to just below the supply fO2.

On descent the ADV will activate dumping large amounts of gas directly from the cylinder into the loop. This too will increase loop fO2. The faster the descent the greater the effect.

On the bottom the pO2 will drop as you work and eventually reach steady state.

__________________
David.

Currently owner of two differently sized ankles.