Aqualung’s ACD - safe or not?

[JackD342]

That's interesting hard to tell from a photo how larg that is...If it closed do you think the reg would be able to deliver enough air at 100 or 130 feet?

I have no way of knowing, but....

I don't think that in the unlikely even the part came loose that it would happen in the middle of a dive. I think it would have happened during assembling gear for the dive, and if the flow is restricted at all affecting performance, you would know something was amiss on the way down and be able to stop your descent long before it became an issue. I don't know if any testing was done at depth with a "loose part" configuration, but it would certainly provide air, maybe just more like a bargain price unbalanced piston at depth, rather than like a Legend.

My take is that the worst case likely is having to call a dive and sort out the issue once topside.

 

[NYCDiverBlue]

which are wet fills and water on the fill whip (notorious in boat fills)

@halocline In your opinion what are wet fills and how do they affect the first stage? Is the problem with wet fills that it causes condensation in the tank which then is pushed out to the first stage when attached? Do wet fills affect other components besides first stage? What is water on the fill whip? I am guessing that the fill whip as just the hose that connects to the tank to be filled and since it is on a boat it is likely there is residual salt water on it that is then blown into the tank. On Wet fills, I found the thread below

Tank fills- Wet or Dry?

Actually, I think I found the answer to my first question in this thread. But the post below is not clear if the water introduced into the tank from wet fill is from the water in the in the tank, condensation or both?
Warning about hot fills!

Filling in a water bath has far greater potential to introduce water into the cylinder than dry filling. <buzzer sound here>
Wet filling introduces a far greater temperature gradient across the cylinder wall, hot inside, colder outside, inducing stress across the cylinder wall. Does this shorten the life of the cylinder, probably not really, but just the opposite of your mis-informed client's impulse, wet filling would shorten the life of the cylinder <buzzer noise here>
Wet filling goes against everything PSI teaches. Not that PSI is the end all-be all of scuba cylinder handling, they are way smarter than me and are willing to do the research that I just don't have time for. <insert buzzer noise here>
Any douchebag who would file QA based on your fill procedures will sue you when he gets hurt because of his own stupidity. Fire the client immediately. It's such a good feeling to let a stressful situation go...

Next time, go to the gas house and watch them fill Oxygen bottles and tell the client how O2 are filled dry...

Thanks
Malcolm

 

[scubafanatic]

It is a question of proper torque for the ACD valve and the yoke fittings. There is a Consumer Safety Notice out which you can find at www.aqualung.com. It applies to Titan LX ACD Yoke SNs beginning with E, F;
to Core ACD Yoke regs with SN's beginning with E, F, G and H prior to H043301;
to Legend ACD Yoke regs with SN's beginning with E, F, G and H lower than H043301.

It should be a ten-minute disassembly/reassembly of the ACD & yoke fittings.

DIN is not affected.

There was apparently one gas shutoff incident related to rocking of the yoke under pressure, where the ACD valve unscrewed.

With only one incident that I'm aware of (third-hand), and Aqualung's retorque request, you should be fine. BUT! Make sure your shop is aware of the Bulletin and is completely conversant with the reassembly and torque settings. The service is no charge. If they don't know about it, change shops!

But IMHO, the whole ACD concept is a solution looking for a problem. What diver needs a valve to keep water out of his first stage? And it won't help the diver who has a wet yoke and reconnects it to his second tank on the boat. As soon as he tightens the yoke and pressurizes, the droplets of salt water are blown past the now open ACD, and get inside the reg anyway.
Old fashioned is better: dry your yoke with a bit of towel before you fit the cap between tanks. It's why I don't let the boat crew ever switch my tank between dives. They're just moving too fast.

Retrofitting to pre-ACD yoke is only possible for a few early ACD legends.

Just go get it checked, if your serial numbers are in the range above.

Here's a reported incident:
Aqualung Legend LX First Stage Failure at depth

I think the ACD can still be useful in certain cases. I've been on dive boats where crews leave off dust caps, and just last year was on a live aboard where all our gear (except for wetsuits) stayed on an open inflatable pangas for the entire week, totally exposed to rain/salt spray, and where tanks were refilled on the pangas by multi-headed fill whips. It was impossible for guests to access gear unless during boarding the pangas on actual dives, otherwise gear was out of reach between dives. So if crew forgot to protect the 1st stage after each fill with their dust caps you'd have regs 'wide open' to accept rain/splashes/salt spray. So it's not just a case of having divers stop being lazy or stupid.

While having the list of affected serial #'s is nice, it doesn't cover those regs that were manufactured correctly, but then later on were serviced Incorrectly, introducing the problem later in their service lives that wasn't there as originally manufactured.

 

[WarrenZ]

In my experience a lot of divers forget the dust cap on their regulator if this is you then the ACD is not the solution. The solution is to re train yourself to put the cap back on Everytime you take the first stage off a tank. The ACD is a backup plan.

By the way I don't have an ACD on any of my regs.

 

[NYCDiverBlue]

I think the ACD can still be useful in certain cases. I've been on dive boats where crews leave off dust caps, and just last year was on a live aboard where all our gear (except for wetsuits) stayed on an open inflatable pangas for the entire week, totally exposed to rain/salt spray, and where tanks were refilled on the pangas by multi-headed fill whips. It was impossible for guests to access gear unless during boarding the pangas on actual dives, otherwise gear was out of reach between dives. So if crew forgot to protect the 1st stage after each fill with their dust caps you'd have regs 'wide open' to accept rain/splashes/salt spray. So it's not just a case of having divers stop being lazy or stupid.

While having the list of affected serial #'s is nice, it doesn't cover those regs that were manufactured correctly, but then later on were serviced Incorrectly, introducing the problem later in their service lives that wasn't there as originally manufactured.

@scubafanatic Thanks for sharing. As a diver whose last dive was 20 years ago and is getting re-certified, I appreciate your story yet I learn a different lesson from it. The lesson I learn is to not let others take care of my gear. There had to be room in the living quarters to store a reg set. If the boat won't give me the time to connect a reg set before the dive then I would choose another operator.

Why in heck would I leave my reg set on a dingy/inflatable panga exposed to the elements, why would I let someone else connect up my gear. While I only sky dived once(civilian) while I was in the military, I am very much part of the school that believes in learning to pack one's own chute because no one can have a more vested interest in me staying alive than myself.

I am very new to the ACD debate and currently side with the "why change a fail-safe system to a fail-fail system" position(willing to change my opinion and joined this thread after it was started as I want to learn about the subject), the point you make has some validity PERHAPS for the rental market in making making rentals safer. YET, one could argue that a dive shop should not be treating their rentals that way but let's say the customers do...then one could argue that the dive shop should be servicing their gear once a year. So then the question are: why would one dive with a shop who is not servicing their gear once a year and to what extent would a proper visual inspection by a rental dive customer prevent usage of a possible defective 1st stage due to corrosion. The previous 2 questions do not address the remaining question, could possible corrosion within a year between annual servicing cause a first stage to fail? Then one would ask does not the dive shop do visual inspections of the first stages during the year?

One question I have is to what extent does a visual inspection of a first stage give a clue as to the internal corrosion which may cause the 1st stage to catastrophically fail? Any insights from those who regularly service 1st stages would be greatly appreciated.

@scubafanatic Feel free to correct any of the points that I make as I fully admit that my knowledge level on this subject is low and I am trying to apply knowledge from disciplines other than diving/regulators to this specific topic. Does anyone think that I am making valid points?

thanks in advance

 

[rongoodman]

@scubafanatic
Why in heck would I leave my reg set on a dingy/inflatable panga exposed to the elements, why would I let someone else connect up my gear. While I only sky dived once(civilian) while I was in the military, I am very much part of the school that believes in learning to pack one's own chute because no one can have a more vested interest in me staying alive than myself.

On that particular trip you let the crew fill, analyze, and connect your tank because they want to minimize the number of times the guests need to climb into and out of the pangas. Over the course of a week it eliminates hundreds of opportunities for a trip-ending slip and fall. (The closest medical care beyond the level of advanced first aid is at least 36 hours away.)

 

[NYCDiverBlue]

On that particular trip you let the crew fill, analyze, and connect your tank because they want to minimize the number of times the guests need to climb into and out of the pangas. Over the course of a week it eliminates hundreds of opportunities for a trip-ending slip and fall. (The closest medical care beyond the level of advanced first aid is at least 36 hours away.)

@rongoodman that makes a great deal of sense. It is all about mitigating risks. Would you advise diving in that area without pangas? would doing so significantly increase the price of the trip or decrease the quality of stay upon the live aboard(i.e. ones with pangas are much more luxurious). Do the pangas allow you to get to dive areas that the livaaboard boat would not be able to access? Or does the panga just get there more economically due to design of the boat(see thread below)? Knowing these things will allow us to plan better.

Thanks for explaining and thanks again in advance.

I had to look up panga. Here is a thread on them.
Panga?

 

[eelnoraa]

On that particular trip you let the crew fill, analyze, and connect your tank because they want to minimize the number of times the guests need to climb into and out of the pangas. Over the course of a week it eliminates hundreds of opportunities for a trip-ending slip and fall. (The closest medical care beyond the level of advanced first aid is at least 36 hours away.)

Titanium

 

[rongoodman]

We're talking about Cocos Island here. Unlike in the Caribbean, there are only two sites where the liveaboatrds can moor, so all the dive sites are accessed by panga. The island itself is uninhabited expect for a few park rangers, so diving with one of the liveaboards is the only way to get there. It's a fantastic place, said to have the second highest shark population on the planet. I'll be back for my third trip out there in a couple of weeks.

After looking at the panga thread, it's clear that the Aggressor Cocos boats use RHIBs instead of pangas, but pangas are what they call them. I don't recall the details about the other company's boats.

 

[Protondecay123]

I have a Legend with the ACD in the first stage. I read some reports about the ACD closing during dives, which has now led me to consider dumping the Legend and picking up a new reg. In the research I’ve done, I don’t know if it’s entirely clear that the ACD failed or there was servicer error in play. In any event, re-thinking things now, the ACD seems like a dumb idea.

Thoughts?

I wouldn’t use any regulator that had the potential to fail in an “upstream” type fashion ( cuts off air rather than free flows (downstream)). But that’s just me. There was a recall over torque a few years ago. Here is a recent report and there are numerous similar ones here if you search right ( use Google). A Catastrophic Regulator Failure: Undercurrent 04/2019