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vjb.knife
May 9th, 2007, 09:43 AM
The new (to the USA) Divator MkII Divelite tank system is approved for use in the USA. Although it has been used in Europe for quite some time we will be able to get it here now. I dove the system back in the 1970's when it had steel tanks and it was very nice in that version. I look forward to seeing and / or owning one in the near future. Even when filled to the US standard 3300 psi it will be about 108 cubic feet. We are so behind in diving technology here it is sad.

Bob3
May 9th, 2007, 01:33 PM
I have a set of the AGA twins, very sweet compact setup.
Trying to find a 4400psi fill back in the '70s was akin to searching for unicorns.
Heck, I STILL have trouble getting a good HP fill.

Dive Right In Scuba
May 9th, 2007, 01:38 PM
Move to IL :D

spectrum
May 9th, 2007, 01:41 PM
As a HP lightweight composite is it small enough in displacement to get the buoyancy in range or do you need to pile on the ballast?

A local LDS can go to 5000 PSI for respirator cylinders. They don't generally bank that high but will run the system up as needed.

Pete

phunk
May 9th, 2007, 03:24 PM
Well it'll have less weight overall but the boyancy swing from full to empty will be the same as any other tank of the same capacity.

fire_diver
May 9th, 2007, 07:10 PM
As a HP lightweight composite is it small enough in displacement to get the buoyancy in range or do you need to pile on the ballast?


I'm not sure of the measurements of the these tanks, but think of this. An AL80 weighs about 35 pounds empty, and still needs about 6 pounds of lead to get it neutral. If you take of 20 pounds of weight in creating a composite bottle, you have to add all the back in lead in the water.

Seems completely the opposite direction from most people moving into steel tanks, and liking them better.

Comrade

spectrum
May 9th, 2007, 08:04 PM
I'm not sure of the measurements of the these tanks, but think of this. An AL80 weighs about 35 pounds empty, and still needs about 6 pounds of lead to get it neutral. If you take of 20 pounds of weight in creating a composite bottle, you have to add all the back in lead in the water.

Seems completely the opposite direction from most people moving into steel tanks, and liking them better.

Comrade

That was my point. However if the ultra high pressure, proportions and perhaps thinner walls drop the displacement enough it could be a good thing.

I doubt that it could approach the efficiency of a HP steel so I suspect it will remain a novelty item for scuba diving. The relationship of displacement and buoyancy is inescapable.

Pete

vjb.knife
May 9th, 2007, 10:52 PM
The displacement of the tanks is the determining factor vs the tank weight. These tanks require an attached weight that goes between them. It is easily attached anytime prior to entering the water.

The higher the tank pressure the smaller the water displaced per an equivalent useable air volume. In other words these tanks are smaller in water volume displacement than a tank operating at a lower pressure and holding the same SCF (standard cubic feet) of air. At their normal operating pressure of 300 bar the Divator tanks hold about 140 standard cubic feet of air.

If you had a normal US tank operating at 260 bar that held 140 standard cubic feet of air it would be much larger and would have to be heavier out of the water to maintain neutral buoyancy than the smaller Divator.

It is Archemedies Principle - a body (or in this case a tank) immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid.

shaggie
May 10th, 2007, 08:05 AM
On another note, don't HP fiberglass tanks have a limited service life of 15 yrs? The ones the fire depts use I'm told do. Of course a good well maintained steel or aluminum tank will live forever as long as it passes hydro and VIP

phunk
May 10th, 2007, 12:00 PM
I'm not sure of the measurements of the these tanks, but think of this. An AL80 weighs about 35 pounds empty, and still needs about 6 pounds of lead to get it neutral. If you take of 20 pounds of weight in creating a composite bottle, you have to add all the back in lead in the water.

Seems completely the opposite direction from most people moving into steel tanks, and liking them better.

Comrade

But if it's higher pressure, it can be smaller and displace less water, so you don't have to add all the weight back in.

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