Apeks Freeflow Control Device

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I am not a tech diver, but I thought the intention of the device, as described on the Apeks site, is to isolate a free flow rather than to use as an on/off switch. So install on your primary, and if that 2nd stage gets you into trouble with a free flow you can shut it down as you switch to an alternate, or even manually open and close it as you head on up.

Here is the issue with that part, not only are you adding an additional failure point but most tech divers (and many rec divers) donate their primary, creating the very really issue of inadvertently shutting down the regulator as you donate it; not good.

Second, if it is a tec dive then you can just shut down your right post and go to your back up with out the need to complicate the primary (see above) . If it is a rec dive, continue breathing from it and surface.

Third, it could be inadvertently shut down during use, possibly at the worst possible time, again, why even add a part that is unnecessary.
 
Upside: you can shut off the gas flow.

Downside: can't breath off it if you forget to open it.
May think tank is empty or reg failured if left closed.
Multiple Additional failure points.
If donating reg person may not be able to breath.
Can cause hose to burst if 1st stage free flows or has seat failure.
They can bump closed (ask me how I know this).
They can gunk up and fail to work.
They can add to jaw fatigue and make hose less flexible in some cases.

I stopped using them over 10 years ago due to upsides being outweighed by downsides. YMMV
:)
 
I had a primary reg free flow on a ascent during an on the fly gas change - I bought a few of them for deco regs and my primary but never installed them....

We back roll instead of jumping and haven’t had any deco regs freeflow, just detuned them......
 
If you shut down a 2nd stage with that device you need to then add an overpressure relief valve so if your IP creeps you dont blow a hose. OPVs are one of the most common leakers of anything scuba.

So not only is the shutoff another failure point but you have to add a 2nd failure point on top of it too.
 
Excuse my ignorance, but if you didn't have this on, what would relive the pressure? The 2nd stage?
Yep..the second should act as an OPV. I only run an OPV on my argon reg. I think I remember some controversy on this over on TDS though. Something about with some regulators the inflator will go first and could result in runaway inflation.

EDIT - here's an old thread on it. Maybe somebody with new information will come along and get us up to speed.

does anyone use OPV's ( over pressure valves ) on their primary 1st-stages ?
 
I've never heard of this before. Well, as a feature of a 2nd stage. Or is it that it just fails if the pressure exceeds a certain amount thus relieving the pressure?
Somebody far more knowledgeable than I will likely be along shortly and get us squared away, but if memory serves the seconds will start freeflowing once the IP gets to around 200 (or higher - prob depends on regs). That's significantly lower than the burst rating of a hose so that's why it works and the Apeks doodad might prevent that from happening and result in a burst hose.
 

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