caveseeker7

Dave summed it up pretty nicely. And very general, as that is really the only simple way answer. The units are so different that detail description of possible problems and all their possible solutions vary for each model.

But just a few more thoughts:

While O-O-G is the most likely problem OC divers face, hypercapnia (CO2 poisoning) as well as hyper- and hypoxia (wrong mix for depth) have occured on OC, too. They are just considerably rarer events.

As mentioned, many problems that occur on rebreather take their time, and a vigilant diver has a good chance to solve them.

Usually rebreathers have plenty of redundancy build into them, such as the normally used automatic gas addition systems backed up with manual systems. Separate power supplies. Tripple redundant sensors for measuring pO2. Redundant displays to convey the info to the diver. But even redundancy varies, there are redundant setpoint controllers and even tripple redundant controllers. In addition there are alternate operating modes, for example using a CCR in SCR mode. And last but not least, OC bailout.

Of course, the redundancy and the more sub systems are added, the more failure points are introduced and the more complex a rebreather gets. Which in and by itself is seen by many as a disadvantage and has led to the development of 'simple' systems.

But there are differences when it comes to flood tolerance loop recoverability.
Differences in gas management, differences in manufacturer provided bailout.
Hence each unit has its own training course.

I suggest reading "Mastering Rebreathers" by Jeff Bozanic as it lists the most common emergency situations as well as their solutions.

__________________
Cheers
Stefan



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