Interestingly enough, I dove a unit today with no MAV, only an ADV, with an ADV shutoff, not my unit. My friend dove his with a MAV only, no ADV. I realized how annoying it was to have an ADV, and how I would much prefer MAV only. I may modify my unit and remove the ADV guts, seal the top, and run a MAV to the now guts-less port. Lungs get tight, smash the MAV. Easy, and no needing to remember to flick on or off the ADV.
Hmmm.....
As for your ADV/MAV, if it's a hydrostatically triggered ADV (second stage on the t-piece, as opposed to a plunger style like the current Meg ADV) then you can likely run it like a MAV by jamming a finger onto the diaphragm. However, a stuck open ADV (think first stage IP creep causing a freeflow) is much more likely than stuck closed. In fact, I don't think I've ever seen a reg fail closed. So, what you currently have is a potential for the ADV to freeflow, which is easy to handle, but no way to shut it down and still maintain the ability to put dil into the unit. Adding a MAV and an OPV on the first stage would allow you to shut off the freeflowing ADV and still maintain the ability to dil flush the unit. Sure you'd be pissing out the OPV on occasion, but you'd lose far less gas than a full on freeflow, and if you bail out to SCR mode, depending on the speed of the IP creep, you might not even trip the OPV since you'd be using the MAV quite a bit.
That being said, I don't dive a JJ and don't know what configuration of flingdingers they've got. I would assume adding a MAV would require two ports on the unit/t-piece/wherever, so that they're independent.
Hmmm.....
As for your ADV/MAV, if it's a hydrostatically triggered ADV (second stage on the t-piece, as opposed to a plunger style like the current Meg ADV) then you can likely run it like a MAV by jamming a finger onto the diaphragm. However, a stuck open ADV (think first stage IP creep causing a freeflow) is much more likely than stuck closed. In fact, I don't think I've ever seen a reg fail closed. So, what you currently have is a potential for the ADV to freeflow, which is easy to handle, but no way to shut it down and still maintain the ability to put dil into the unit. Adding a MAV and an OPV on the first stage would allow you to shut off the freeflowing ADV and still maintain the ability to dil flush the unit. Sure you'd be pissing out the OPV on occasion, but you'd lose far less gas than a full on freeflow, and if you bail out to SCR mode, depending on the speed of the IP creep, you might not even trip the OPV since you'd be using the MAV quite a bit.
That being said, I don't dive a JJ and don't know what configuration of flingdingers they've got. I would assume adding a MAV would require two ports on the unit/t-piece/wherever, so that they're independent.