Kennyscot
Guest
Aqua Lung/Apex has a anti free flow device that you attach to your hose. Does it work well?? How does it work?? I dive in cold water and free flows can be a problem. I've never had one and don't care to..
Anti-Free flow device
- Thread starter Kennyscot
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Yeah.... what quarrior said.
I've been using Apeks regs and even in water in the mid 30's (F), have not had freeflow problems as long as I don't do stuff like breath from them on the surface when the air temp is already well below freezing. I've never had a freeflow problem with them once submerged, even when doing stuff like inflating a lift bag. I keep the adjustments on the backup reg turned to minimum which probably helps as well.
I've been using Apeks regs and even in water in the mid 30's (F), have not had freeflow problems as long as I don't do stuff like breath from them on the surface when the air temp is already well below freezing. I've never had a freeflow problem with them once submerged, even when doing stuff like inflating a lift bag. I keep the adjustments on the backup reg turned to minimum which probably helps as well.
I'll actually answer your question.... I have one and have installed it on my reg (ATX-200). Never found the need to actually activate it. I took it off. It is a very simple device and I don't buy the "additional failure point" argument. It's an argument devised by cave divers, and I don't think it's all that big for your normal recreational diver.
It's a two part device. There's a metal tube that screws between your second stage and the hose. Inside of this is a permanently installed metal piece that would block all airflow except that there's a bunch of perforated holes on the outside of this tube and on either side of the obstruction. So, as is, if the reg is turned on, then it will freeflow through the perforations. So, the second part is a plastic sheath that wraps around the tube, slides back and forth, and can either cover both sets of holes or uncover both sets. There's a small chamber inside this sheath, so air can flow from one set of perforations to the other. When you need to choke it off, slide the sheath and cut off airflow. There's a double set of o-rings on either side of the sheath. If closed and subject to a first stage freeflow, the hose won't explode.... It just leaks out through the seals in the sheath.
I encontered two problems with it. First, it's pretty easy to accidentally choke off the flow while you're gearing up. It's very simple to just move the sheath and fix that problem. Second, it reduces the flow rate. I put it on a flow meter, but I don't remember how much it decreased the flow. Needless to say, I needed a flow meter to see it - not noticable otherwise.
With a high-end reg, I don't see a need for it. It might be useful on a Scubapro, though....
It's a two part device. There's a metal tube that screws between your second stage and the hose. Inside of this is a permanently installed metal piece that would block all airflow except that there's a bunch of perforated holes on the outside of this tube and on either side of the obstruction. So, as is, if the reg is turned on, then it will freeflow through the perforations. So, the second part is a plastic sheath that wraps around the tube, slides back and forth, and can either cover both sets of holes or uncover both sets. There's a small chamber inside this sheath, so air can flow from one set of perforations to the other. When you need to choke it off, slide the sheath and cut off airflow. There's a double set of o-rings on either side of the sheath. If closed and subject to a first stage freeflow, the hose won't explode.... It just leaks out through the seals in the sheath.
I encontered two problems with it. First, it's pretty easy to accidentally choke off the flow while you're gearing up. It's very simple to just move the sheath and fix that problem. Second, it reduces the flow rate. I put it on a flow meter, but I don't remember how much it decreased the flow. Needless to say, I needed a flow meter to see it - not noticable otherwise.
With a high-end reg, I don't see a need for it. It might be useful on a Scubapro, though....
It's actually a pretty useless device and not real effective at solving the problem of a cold water freeze flow.
Having a second stage freeze up is extremely rare and that is the only problem it would solve. It is far more common for the first stage to freeze up causing an increase in intermediate pressure. The excess pressure then HAS to vent through one or the other of the second stages or a hose will rupture and vent the excess pressure that way.
So...if you block off the excess air freeflowing from a second stage with some type of valve, it will just vent through the other second stage as that would now be the path of least resistance. If you block off that one, then the pressure will just increase in the hose until it ruptures.
Having a second stage freeze up is extremely rare and that is the only problem it would solve. It is far more common for the first stage to freeze up causing an increase in intermediate pressure. The excess pressure then HAS to vent through one or the other of the second stages or a hose will rupture and vent the excess pressure that way.
So...if you block off the excess air freeflowing from a second stage with some type of valve, it will just vent through the other second stage as that would now be the path of least resistance. If you block off that one, then the pressure will just increase in the hose until it ruptures.
Kind of amazing that they sell such a valve without an overpressure feaure, like a burst disc.
It's also amazing how easy it is to criticize a piece of equipment you've never even seen before. Personally, I don't use it, but I actually have it sitting here in front of me.
It's not a perfect seal when it's closed. As I said before, the hose wouldn't rupture. It will leak out around the sheath. I have it right in front of me. If it's closed, I can actually blow hard enough to make air leak from around the edges of the sheath. It is a Freeflow Control Device, not strictly a cut-off valve.
It's not a perfect seal when it's closed. As I said before, the hose wouldn't rupture. It will leak out around the sheath. I have it right in front of me. If it's closed, I can actually blow hard enough to make air leak from around the edges of the sheath. It is a Freeflow Control Device, not strictly a cut-off valve.
It would kinda suck if your buddy went OOA and you accidentally activated this device in the process of donating your regulator, leaving the entire team with only a single working second stage..
aquaoren
Contributor
Not that I'm interested in the free-flow device but having a good cold water reg doesn't mean they can't freeze or freeflow.Quarrior:
I brought my Apeks DS4/ATX 50 to freeflowing when dumping air from my tanks to get my weighting tuned.
Last dive, my buddies Zeagle freeflowed on him.
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