| Re: PO2 Set-points (WHEN!)
Samisus, to help answer your question about set points. I like to switch to my high set point (HSP) approx 15-30' above my max depth. If you switch to HSP at the bottom then you will have to vent excess gas out of the loop to keep min loop volume, (the O2 being injected will help to offset the compression of gas in your loop and the pressure increase will help raise your PO2 to the HSP), you should find it aids with learning buoyancy control.
There is no reason why you can't use the auto set point switch, when you're learning this is a great tool so you don't forget to make the switch during the decent, especially starting out when you're mind is thinking about 100 things at the same time. Just make sure you don't get complacent and forget the most important rule of CCR diving, make sure you know your PO2. So on decent make sure your watching that handset especially when you hear that solenoid fire.
As for switching to your Low Set Point (LSP), when training you can progressively shallow up your switch. Buoyancy control of course is one of the biggest changes from OC to CCR and learning to maintain min loop volume makes the biggest difference on your buoyancy and it just takes practice. Do what your instructor briefs you on. But it's often a basic teaching technique to make the LSP switch the first couple of days at around 26 feet, then shallow it up to 20' the next day or 2 then on the final day maintain HSP all the way up to 16 feet.
There have been lots of suggestions for venting excess gas out of the loop when first starting out venting through the nose if often the best way to stay in control of how much gas to "burp" out. As you learn and dive more on the unit you may start learning to vent out from around the mouthpiece. Just remember too loose of lips will allow water into the loop, it's all a matter of practice and finding what your comfortable with. |