Avelo--I guess there's no need for me to recommend fundies anymore....

[wetb4igetinthewater]

Its supposed to be at DEMA this year. So for the 2 people from ScubaBoard going, they may want to check it out.

 

[Angelo Farina]

In the seventies a scuba tank system with integrated buoyancy control was commercialised by Scubapro, called the Scubasystem:

https://www.blutimescubahistory.com/sites/default/files/cataloghi-completi/SCUBAPRO-Catalogo-1977---17.jpg

 

[wetb4igetinthewater]

I was exposed to this idea a couple of years ago when it was being developed, I really didn't get much more info than what we have today. I assumed it was a composite wrap cylinder of some sort that could be removed from the shell and sent to hydro.

My understanding was that the magic of this device was in the hydraulic pump technology brought from the fracking industry.

I may have said too much already...

Hey, can they make a version for rebreathers/counterlungs?

Might make my life easier as I get used to buoyancy control on my P2.

 

[lowwall]

The animation shows the inner "cylinder" being resized as the tank is filled/drained with water. Assuming that's a realistic representation, that implies the air is basically in a balloon inside the tank. Outer shell will have to handle the pressure of the most compressed state (ie, at a full 300 bar fill + however much volume of water you need to add to become neutral in order to decsend). This also implies the pump needs to handle pressures in excess of 300 bars.

Concerns about loss of battery/pump I don't see so much as a problem. As long as you still have air left the "dump valve" simply uses the pressure of the gas to push the water back out, and voila, buyoancy. And it appears that the aim is to be neutral anyway, so should always be able to swim up at which point wetsuit decompression etc will start making you marginally positive.

I suspect the animation was trying to convey the idea of water entering the outer shell rather than being an accurate rendition of what is occurring within the system.

It's hard to imagine a membrane that can live in saltwater for years, be flexible enough to accommodate several inches of movement and be capable of withstanding 300 bar. That's roughly 100 tons of pressure over an area the size of the base of a scuba tank. A thick enough sheet of Dyneema cloth could theoretically handle the pressure, but how would you go about bonding it to the stub tank (or tank valve)?

 

[NothingClever]

In the seventies a scuba tank system with integrated buoyancy control was commercialised by Scubapro, called the Scubasystem:

https://www.blutimescubahistory.com/sites/default/files/cataloghi-completi/SCUBAPRO-Catalogo-1977---17.jpg

That advertisement (upper right) was written by a frustrated author with about three glasses of red wine in her.

 

[rmorgan]

4350 psi—so not AL or steel. The Luxfer 106 composite cylinder matches these specs: 15kg/34lbs, 300b/4350psi service pressure, DIN only. Humping metal tanks sucks as much now as when I started doing it in 1980; this rig sounds great! If they do roll it out at DEMA this month as they say on Facebook, there’ll be a lot of interest—and a lot of naysaying BCD manufacturers. Fun!

 

[Wibble]

I suspect the animation was trying to convey the idea of water entering the outer shell rather than being an accurate rendition of what is occurring within the system.

It's hard to imagine a membrane that can live in saltwater for years, be flexible enough to accommodate several inches of movement and be capable of withstanding 300 bar. That's roughly 100 tons of pressure over an area the size of the base of a scuba tank. A thick enough sheet of Dyneema cloth could theoretically handle the pressure, but how would you go about bonding it to the stub tank (or tank valve)?

One bar is one kilogram on one square centimetre.

100 bar is 100kg on one centimetre. That’s the entire weight of a fat bloke on one dime.

300 bar would be the 600 pound gorilla on a dime.


On the other hand there’s the simple, reliable, easy to use Buoyancy Control Device. Fancy that.

 

[mwerle]

I suspect the animation was trying to convey the idea of water entering the outer shell rather than being an accurate rendition of what is occurring within the system.

It's hard to imagine a membrane that can live in saltwater for years, be flexible enough to accommodate several inches of movement and be capable of withstanding 300 bar. That's roughly 100 tons of pressure over an area the size of the base of a scuba tank. A thick enough sheet of Dyneema cloth could theoretically handle the pressure, but how would you go about bonding it to the stub tank (or tank valve)?

Those were pretty much my thoughts.. hence my initial claim it was just an idea on paper (that, and the fact that an IP/patent company seems to own it..)

If it's a double-shelled solid construction instead, with a proper inner tank and an outer ballast shell, then I guess there's a fairly limited amount of water which can be added/purged as balast. I wonder how many KG worth? 1 litre ~= 1kg.

Anyway, we've been told it's a real thing, so looking forward to finding out some actual facts once they show this off.

 

[Wibble]

Anyway, we've been told it's a real thing, so looking forward to finding out some actual facts once they show this off.

Isn’t that how a submarine works?

 

[mwerle]

Isn’t that how a submarine works?

Kinda - except they don't keep the compressed gas inside the ballast tanks so there's no need for anything fancy. The ballast tanks on a sub don't even need to be pressure vessels as their internal pressure always matches the ambient pressure.

The concept is simple enough; it's engineering it into a tiny self-contained package that's the interesting bit.