Titanium scuba tank

[Jim Lapenta]

You may also want to check out a third lung.

Can you be an instructor and use this?

 

[pescador775]

There are plenty of light weight tanks out there. These range from low pressure oxygen tanks to very high pressure kevlar, glass, graphite wrapped tanks used for various purposes including SCBA used by fire fighters, etc. Neck thread size could be a problem. Most of them use an NF thread which varies in size depending on the application. Some of the old SCBA tanks used a 1/2 NPS (O ring) but they were steel and fairly heavy compared to capacity. So, a special adapter might have to be fabricated in a machine shop to accomodate a SCUBA valve. Well, there are some SCBA tanks out there with 7/8 NF which is the same size as used on the older, HP SCUBA tanks which were used exclusively with the 300 bar DIN, SCUBA valve. You may wish to explore that area further. The buoyancy may cause a tendency for awkward balance underwater but should be managable with correct weighting.

 

[WD8CDH]

Carbon fiber tanks have a 15 year from manufacture date life.

How much air do you want to carry and how much weight can you carry on your back? I have access to a few unusual DOT tanks that are very light but can be used under water.

FYI, a standard aluminum 80 is about 32 pounds empty without valve.

 

[akdeepdiver]

I have heard rumors that a company in Japan is working on a Titanium Tank. But, currently it is in the process of getting the Special Permit from the DOT. That can take between 1 and 10 years. Of course like I said, this is all 2nd or 3rd hand.

 

[WD8CDH]

There are several ways to reduce stress on your back.
1. Limit the air that you carry using conventional tanks.
For example, single aluminum 50 (21.2Lb w/o valve), AL40 (15.3Lb), AL30 (11.3Lb),
Steel 45 (17.6Lb)

2. Use multiple tank rig using conventional tanks that places the weight closer to your
body reducing stress.
For example, triple or quad steel 20s, double steel 45s, double or triple AL 30s or 40s.

3. Use a regular rig but make a backpack that transfers the weight to your hips like a
hiking backpack

4. Use light weight specialized industrial tanks.
Disadvanteges.....Would need custom machined valve adapters. May have minimal
trim problems because the buoyancy would be near your head.

5. Use "exotic" firefighter tanks that are high pressure and light weight.
Disadvantages.......Not a lot of shops that can fill 4500psi tanks. Tanks not rated
for underwater use. Very buoyant, would tug on your straps and cause trim
problems.

6. Use Euro composite tanks.
Not DOT certified. Most shops won't fill them.
http://www.interspiro.com/_downloads/98607C01_Divator_Lite_product_leaflet_L.pdf

I use a combination of #2 and #4.


I used to use 7,500psi titanium tanks but there was only one place within 500 miles of me that could fill them.

A rebreather would be a good choice but I don't know of any other than homebuilts that would be light enough.

 

[JahJahwarrior]

Why isn't anyone else considering sidemount? You could carry each tank to the water by itself, reducing total weight to be carried at any one time. You could also dive with smaller cylinders, say al40's, to give you the same total gas supply as a single al80. Or, get two of those light HP steels. You could also get your buddy to haul the things to the water for you. Much easier than getting tanks not DOT or underwater rated or which require very high pressure filling ability, even though it might behoove you to take a class in sidemount diving.

 

[SeaHound1]

Counterproductive is right, you'd have a lighter tank and have to wear more lead to keep it negative. Your best bet would be a European steel tank similar to a LP 85, and fill it to 3000psi. In the US they are only rated at about 2500psi because of DOT, but have a higher rating in their native country.

 

[PCBCaptChris]

I just looked up the Luxfer 106. It looks like all they did was wrap an aluminum 80 in fiber and get it rerated as a 106. With a 15 year life span it sounds like a good direction to move in for them... I think the cost/benefit of this first edition is very limited at best. Given the negligable return for all the effort to make sure it is at 4300 and the wear and tear on the 1st stage. If they could get the size down it would offer more atvantage over traditional tanks for the trouble. I think that would require wrapping the bottom, which would bring tank longevity problems with it...

Titanium, dependent upon the large scale production cost, might be a lot more durable.

If they could get fiber wrapped more main stream I think that is where it is at.

 

[WD8CDH]

Counterproductive is right, you'd have a lighter tank and have to wear more lead to keep it negative. Your best bet would be a European steel tank similar to a LP 85, and fill it to 3000psi. In the US they are only rated at about 2500psi because of DOT, but have a higher rating in their native country.

The lighter tanks are not totally counterproductive. The Luxfer 45 CF carbon fiber tank weighs 13.7 pounds WITH the weight needed to be made neutral empty (5.9 without valve or weight), Luxfer 40 weighs 17.5lb, OMS steel 45 weighs 17.6, Catalina 45 weighs 21.6lb, and Luxfer 50 weighs 22.5Lb including weight needed to make them neutral. The lighter tank still saves about 4 to 8 pounds compared to the other 45 cubic foot tanks.

I ruled out both the euro steel tanks and overfilling DOT tanks because either is illegal. And a LP85 would probably be too heavy for him anyway.

 

[WD8CDH]

I just looked up the Luxfer 106. It looks like all they did was wrap an aluminum 80 in fiber and get it rerated as a 106. With a 15 year life span it sounds like a good direction to move in for them... I think the cost/benefit of this first edition is very limited at best. Given the negligable return for all the effort to make sure it is at 4300 and the wear and tear on the 1st stage. If they could get the size down it would offer more atvantage over traditional tanks for the trouble. I think that would require wrapping the bottom, which would bring tank longevity problems with it...

Titanium, dependent upon the large scale production cost, might be a lot more durable.

If they could get fiber wrapped more main stream I think that is where it is at.

I don't think that 4500psi even with very heavy use is much of a problem with todays regulators. I personally have used 1970 Conshelf and Poseidon regulators at 4500psi extensivly and the Poseidon at 7,500psi for dozens of dives. Almost all new regulators are now rated for 300 bar.

Luxfer makes several full wrap tanks (45, 65 and 87CF) that if produced with a different resin would make great SCUBA tanks. If you look at the link that I posted for the composite SCUBA tanks, you will se that they solved the buoyancy problem with a quick connect V weight. With the weight, they are still lighter than the equivilent steel or aluminum tanks. Another advantage is you only need to carry one V weight per diver not the added weight for each rig. With multiple sets of tanks per diver, that is a substantial weight savings.

What I think would be better would be 3442psi aluminum tanks made from a stronger alloy. The stronger alloy is already being used to make some DOT tanks and is not succeptable to SLC like the old aluminum alloy that was used prior to the current 6061 alloy. This would give tanks with a similar capacity for size as steel tanks but a lighter unballasted weight without the expense and ultra high pressure of carbon fiber tanks.