Tusa APA Failures - Potentially Dangerous?

[Skoobaskunk]

I own a Tusa Conquest II, which I like as a hybrid BC suits my needs and which on the whole has served me well since purchase, that is apart from the APA (Active Purge Assist) power inflator.

I was on a drive recently and the APA failed mid-dive. I was able to remove the BC underwater and could see that air introduced into the bladder was just pouring out of the dump valve portion of the APA, compromising the air tight integrity of the air cell. Luckily I was only in 15m of water (2nd dive of the morning) so was able to make it safely to surface without having to dump weights, and as I tend to introduce minimal amounts of air into my BC managed to stay neutrally buoyant. The challenge was trying to maintain buoyancy at the surface, but I was able to make it back onboard safely by surfacing under the ladder.

However, this is the second APA failure that I've experienced since owning this BC, the first gave out whilst I was rinsing the BC and I noticed that the same dump valve portion of the APA was leaking when it was submerged in my rinse tank. I purchased another inflator, swapped it out and thought little off it at the time (other than the cost, these things are about $135). However, a 2nd APA failure has now led me to think that this is an extremely high failure rate given that I maintain my kit, try my best to keep it out of the sun, rinse it after every dive and I had the 2nd APA serviced when I had my regs serviced at their last interval as a precautionary measure.

The issue and the main concern with this inflator is that when the pneumatic dump valve portion of the hose assembly fails, (a) the bladder to fills with water and (b) the dump valve fails open, causing air to be vent from the top of the pneumatic dump valve, thus resulting in the diver to lose and/or being unable to maintain buoyancy. I figured that I had been extremely unlucky to experience two failures in a couple of years, but I was exchanging messages with a friend last week that also own this same BC with this model of APA and he has experienced the exact same failure, which seems to indicate an inherent problem with this inflator which could result in loss of life.

Has anyone else had any issues with the Tusa APA, our regional Tusa rep (who to his credit has been very helpful) advised that they hadn't had any reports of issues with these inflators?

 

[emoreira]

I´m a dive instructor in a dive school, and I usually receive gear from divers to do repairs, as I'm also in charge of the maintenance and repair of our own gear.
Once a diver brought a TUSA Selene BCD equiped with that APA inflator. She was complaining that the BCD was self inflating.
That was the first time I've seen that APA mechanism and I was astonished of the complexity of the whole inflator. See TUSA Active Purge Assist
It seems that normal rinsing is not enough to rinse sea water leftover after a dive.
TUSA is famous for the increased useless complexity of their gear, in a world where simplicity and robustness is primal. TUSA designed a solution for a non problem.
These type of things should be specially considered when buying gear.

 

[wnissen]

When you rinse, do you purge the inside of the BCD bladder with fresh water? Even when I haven't been using the dump valves much, I still find a good amount of seawater inside. I flush with a hose into the oral inflate and a couple of times and make sure to drain through the inflator and any other dumps. Otherwise you can get some pretty impressive salt crystals over time. But I agree, two failures of the same thing means it's not serving you well.

 

[emoreira]

I've recently came across a TUSA S-80 second stage. It's an unbalanced second stage, though it's adjustable and has a built in mechanism that avoids free flow when submerged upside-down.
I was, once again astonished with the complexity and the amount of pieces inside a simple unbalanced second stage.
The reg set came also with an S-60 Octopus (A ScubaPro R380 octopus with a dedicated flex purge cap).
R380 second stage is also an unbalanced second stage and it has all the required parts to work, though the parts count is almost one half of the parts count of the S-80.

 

[Skoobaskunk]

When you rinse, do you purge the inside of the BCD bladder with fresh water? Even when I haven't been using the dump valves much, I still find a good amount of seawater inside. I flush with a hose into the oral inflate and a couple of times and make sure to drain through the inflator and any other dumps. Otherwise you can get some pretty impressive salt crystals over time. But I agree, two failures of the same thing means it's not serving you well.

Absolutely, I typically fill the BC with a litre or two fresh water twice, once diluted with McNett BC life to remove as you say any salt water crystal build up, and a second time with half a crushed tablet of Steramine to lightly disinfect the inside of the bladder before storage, each time flushing through all dump valves, oral inflator, etc, etc. That said your question has made me realize that to effectively clean the APA it really needs to be pressurised when rinsed, so as to be able to activate the pneumatic dump valve mechanism, and that’s going to be a real paint to do that each time.

 

[Skoobaskunk]

I've recently came across a TUSA S-80 second stage. It's an unbalanced second stage, though it's adjustable and has a built in mechanism that avoids free flow when submerged upside-down.
I was, once again astonished with the complexity and the amount of pieces inside a simple unbalanced second stage.
The reg set came also with an S-60 Octopus (A ScubaPro R380 octopus with a dedicated flex purge cap).
R380 second stage is also an unbalanced second stage and it has all the required parts to work, though the parts count is almost one half of the parts count of the S-80.

Yeah, I came across this thread TUSA Active Purge Assist when researching my specific issue where someone had requested a service guide/schematic for the APA and I was surprised that it contained 4 rings and 10 O-rings. It also reminded me that before the BC was last serviced, it too had started to self inflate and that's what prompted me to get the BC serviced at the same time as my reds.

 

[Skoobaskunk]

Like I said, I like the BC itself so I'm trying to find a 3rd party inflator assembly that will retro fit it, which is proving difficult and the 'simpler' (at least I'm going to assume that it's simpler by design) Tusa BCU-313 power inflator comes out at $122, but I think I'd prefer to try another brand given the issues to date.

 

[wnissen]

Absolutely, I typically fill the BC with a litre or two fresh water twice, once diluted with McNett BC life to remove as you say any salt water crystal build up, and a second time with half a crushed tablet of Steramine to lightly disinfect the inside of the bladder before storage, each time flushing through all dump valves, oral inflator, etc, etc. That said your question has made me realize that to effectively clean the APA it really needs to be pressurised when rinsed, so as to be able to activate the pneumatic dump valve mechanism, and that’s going to be a real paint to do that each time.

Wow, that is a very thorough cleansing. I rinse 2-4 times, until the water tastes "sweet". Good luck with getting a set up you're happy with.