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I left my ADV on my rEvo, even though my instructor and most of the local rEvo divers have theirs turned off. When I finally turned it off (after 130 hours), there was a world of difference/improvement to my bouancy and the way I dived the unit. In fact I realised I was using the ADV to maintain bouancy (more than loop volume) that mean't the solenoid was kicking in to get back to setpoint, and then I would end up burping a whole lot of O2 out the OPV or through my nose / side of my DSV.
Now that I have turned it off, bouancy and gas consumption have improved dramatically.
I have only done 2 dives post course on the Chop, but I forgot to turn ADV off using in line shut off (at bottom depth) and bouyancy was OK, but went through significant amounts of O2, The solenoid clicked in after each dil addition (* where it doen't click in so much on the rEvo because of the Constant Mass Flow / leaky valve). So I need more practice and get use to using in line shut off.
But I guess there isn't alot of difference between 1) turning ADV off / just adding dil through the MAV and 2) having an in line shut off added.
The one area I would say it may be useful to have a inline shutoff/ADV for Dil when you can turn it on laying line and being able to add dil without using your hands. But on the rEvo the CMF is adding O2 all the time so its not as cyclical a process adding using an ADV / then having the Solenoid fire, as say on the chop (which doesn't have a leaky valve/CMF).
I guess its a cost benefit analysis of having the ADV fire when inverted even though you don't want it to, and the extra 1 minute it takes to stop add dil check bouancy and continue on with the line laying task.
You can just detune an ADV so that it only fires when it is completely empty and you are sucking. That is how I run all of mine.
In that scenario, you don't get unwanted addition, you don't have to turn it on and off, and you still have gas to breathe should you ever have a armful of chain, doing a negative entry, plunging towards the bottom only to find your MAV flipped up behind you when you splashed.
That was the exact scenario that made me install an ADV back onto my unit. I don't ever use it, but if I need it, it is still there.
It is already pretty detuned. Suck, hit a wall, suck really hard and then you get something. Slightly more than nothing.
I'm thinking more of the ascent. I'm wondering how much the ADV is being the OPV for the IP and bleeding DIL into the loop when I am trying to get DIL out of the loop. Never thought of it until this post. I can think of a few dives where that was likely what was going on.