justinthedeeps
Contributor
What is the "What?"What?
If you are on a CCR--at the surface--the minimum percentage of oxygen in the loop to avoid having to worry about hypoxia is--OFFICIALLY--40%. A.k.a. a ppO2 of 0.4. But 70% is safer. And you can easily abide by this on hypoxic diluent, or even a pure helium diluent, by maintaining setpoint.
Some agencies/manufacturers even want you doing a routine 100% O2 flush at the surface, because of prior drowning incidents.
Possibly counter-intuitive for people who are thinking about numbers for minimum survivable open air & OC mixes.