Looking through the on-line version of the AP Evolution manual I came across the following (p87)
"When deeper than 20m too much O2 may be added using this method..."
The paragraph is part of a section dealing with actions to be taken with a high Oxygen (ppO2) warning is displayed.
The problem I am having (bear in mind I don't [yet] own an AP machine) is that I have always considered cylinder valves to be pretty much constant flow rate devices (for "constant" pressure) when fully opened. If I am right then opening a cylinder valve for a fixed (short) time will add a fixed quantity of O2 (i.e. a fixed number of molecules). At a certain ambient pressure this would equate to a fixed increase in ppO2.
I would therefore have thought that as the depth increases that the increase in ppO2 would be less.
It would appear from the statement in the manual that the cylinder adds more O2 at greater depth.
Someone please put me out of my misery and explain where I'm going wrong!
Ant S