2 O2 and Diluent inflators on 1 counter lung

[padiscubapro]

Although I am not CCR trimix trained I will give you my best understanding of it. Your onboard gas is very limited. I carry 20cf of dil and O2 on my rebreather plus 30cf OC bailout gas as a sling. Let's say I had a failure of the o2 delivery system, could be lost gas or electronics etc. I could use my OC and bailout, but if I needed more time a better option is to run my unit as a semi closed rebreather which allows me to use my 20cf more efficiently. I could also, if I had an extra port, plug in my 30cf bailout and use it as diluent for scr bailout (offboard). Another option is to use different gasses as diluent for different legs of a dive but that is outside my level of training and maybe padiscubapro will jump in on that aspect of it.

Dave a personal suggestion.. Although a 40cf bottle is larger than a 30, its generally a more confortable and stable bottle to dive with.. the 30s are a bit to short and if you go vertical the bottle will generally end up in the middle of your body where 40cu ft bottles stay where you put them..

A second port makes it easier but is not necessary most people just disconnect the onboard whip and plug in an off board whip.. Having it as a backup is questionable.. if its because the button is sticky, well maybe, but if it fials open (its not going to fail closed) you would have to shut down the onboard supply (you couldn't disconnect it) and now you have to use an off board supply.. I think the second is actually a bigger failure point because many people who have these enter the water with it disconnected then hook it up.. the first time they use it they blow water right into the valve.. after a while you getr corrosion and get a leaky valve!