300 Bar (4,500) psi tanks?

[snowmaker]

To Buoyant. There's a reason people like steel tanks.

 

[A34735]

From the repleys sofar,you guy's have a problem.
4500 psi or 300bar is quite common overhere.

But would your tanks be good for diving....
Whatever you lost in weights on your tanks,you will be replacing with weights on you belt.
4500psi/300bar is just fine (for us) but get it in steel tanks.They are heavier then normal tanks so you can cut on the weightbelt.

And as for your regs. all new Din (300bar)regs will do just fine.

Evert:

Your European perspective is very helpful: when I left the UK, DIN fittings and 300bar regs were becoming popular. So I thought taking tanks from 232 to 300 bar would be the obvious evolution. Seems like Europe has embraced this, but adoption in the US is still patchy.

But...I don't like transferring the weight from my belt to the tank. If I have to drop my belt, I want to feel a real difference in my buoyancy (with an empty tank pressing the 'Inflate' button will be a waste of time). And if the weight is on my back, it's going to be difficult to dump.

All the best,

Nigel

 

[scubafanatic]

...I guess the question is, what are the odds you've actually invented a revolutionary new scuba tank design/application, that nobody else in the world has thought of ? Is it that you are brilliant...or might it be you've overlooked something ?

 

[tgsmith]

...I guess the question is, what are the odds you've actually invented a revolutionary new scuba tank design/application, that nobody else in the world has thought of ? Is it that you are brilliant...or might it be you've overlooked something ?

CF cylinders have been used before. The Huatla cave expedition used carbon fiber cylinders back in the 80's. In addition, you'll find old Interspiro CF 4500psi cylinders on ebay from time to time. IIRC the Mk15 rebreather has CF spheres available to it.
Problem is:
1) Government mandated 15 year life span.
2) CF wrap gets banged up and you're out of a cylinder.
3) Most people didn't like the buoyancy characteristics. I read somewhere(so don't quote me) that they tended to be 12-14lbs positive when empty. That's a LOT of extra weight you're going to need to carry.
4) Expensive to purchase.
5) Have to get hydro inspection performed more frequently(I think every 3 years).

So, nothing new. They didn't sell well, that's all.

 

[tgsmith]

For the interested:
Google Image Result for http://www.stoneaerospace.com/about-us/pictures/1980_3.jpg

 

[WD8CDH]

CF cylinders have been used before. The Huatla cave expedition used carbon fiber cylinders back in the 80's. In addition, you'll find old Interspiro CF 4500psi cylinders on ebay from time to time. IIRC the Mk15 rebreather has CF spheres available to it.
Problem is:
1) Government mandated 15 year life span.
2) CF wrap gets banged up and you're out of a cylinder.
3) Most people didn't like the buoyancy characteristics. I read somewhere(so don't quote me) that they tended to be 12-14lbs positive when empty. That's a LOT of extra weight you're going to need to carry.
4) Expensive to purchase.
5) Have to get hydro inspection performed more frequently(I think every 3 years).

So, nothing new. They didn't sell well, that's all.

As a User of both composite tanks and 300 bar and higher tanks, a few comments.

1. There are some DOT CF cylinders that are 30 years and there are some EURO composite cylinders that have unlimited life, as long as they pass hydro and visual.

2. True, but composite tanks are sturdier than most people think.

3. While CF tanks are buoyant, at least for 300 bar CF tanks, even with the added weight to make them neutral or slightly negative, the combined weight is still less than conventional SCUBA tanks.

4. definitely

5. Most CF tanks are 5 year hydro. It's mostly the older fiberglass composite tanks that are 3 year.

What I think would make an excellent 4500psi scuba tank would be the 7000 series aluminum alloy that Luxfer uses on some of their medical oxygen tanks. The 7000 series alloy is so much stronger than 6061 alloy that if tanks were to be made with the exact same dimensions and wall thickness as conventional 6061 alloy aluminum SCUBA tanks, they could easily be rated for a service pressure of over 4500psi. The buoyancy characteristics would be better than composite tanks without adding weight. When weighted, they would still be far lighter than conventional tanks. Unlimited life. High corrosion resistance. Should be cheaper than HP steel tanks. No internal rusting. Rugged. High capacity.

 

[A34735]

Thanks to all of you for the thoughtful replies...
ATB,
Nigel