Non-steel, non-aluminum scuba tanks

[Filipe Marques da Costa]

I'm wondering if current tank material engineering has already peaked with steel/aluminum tanks? I mean is that as good as it gets? Or is there something, some metal or polymer that will handle the pressures, be tough and has the adequate buoyancy characteristics and at the same time bring something to the table when in comparison with current tanks (say, less weight)?

I'm wondering if anyone here ever tried or handled or heard about other scuba tanks that are not made of steel or aluminum or carbon.

 

[grantctobin]

There exist inconel tanks, but otherwise no, not really. Physics is physics.

 

[tbone1004]

everything is about displacement. Let's call aluminum tanks neutrally buoyant and steel tanks slightly negatively buoyant when empty. If they were made to be lighter like the carbon fiber bottles that are out there then they would be extremely positively buoyant which is not advantageous. The only practical way to make them lighter is to make them smaller which means running them at higher pressures. This causes accelerated wear on the first stage and more importantly starts down a steep slope of Z-factor for non-linear compressibility of a gas which means a tank at 6000psi that you would think would hold 2x that of the same tank at 3000psi has a compressibility factor of ~1.2 which means it holds ~1.7x that of the 3000psi tank. That compressibility factor is a killer.

 

[lowwall]

I'm wondering if current tank material engineering has already peaked with steel/aluminum tanks?

Yes.

Lighter weight gives you no advantage as you just have to make up the difference with ballast. AL is worse than steel during a dive, but offers advantages topside in lower cost and greater corrosion resistance.

 

[tbone1004]

There exist inconel tanks, but otherwise no, not really. Physics is physics.

and those exist primarily for the non-magnetic properties for EOD use

 

[broncobowsher]

Even the carbon fiber tanks are around an aluminum liner. Metal has an unlimited lifespan. The composite materials age poorly (long term, none will be serviceable by the age of 20 years)

 

[rx7diver]

I'm wondering if anyone here ever tried or handled or heard about other scuba tanks that are not made of steel or aluminum or carbon.

I remember reading in (the defunct?) Underwater USA magazine/newspaper in the early 1990's about titanium scuba cylinders. I think someone was importing them from the Soviet Union (or contemplating importing them). I think I recall that two sizes were described, the smaller cylinder having dimensions similar to the old Scubapro "Slimline" 63 or 66. I made a note on the cylinder spec page of my Cave Diving Manual, I think, because of my "forever" interest in smaller, lighter, and simpler scuba. I'll look this up when I return home this evening.

rx7diver

 

[rx7diver]

I just googled "titanium scuba cylinder tank" and the first "hit" is from a Scubaboard thread: Titanium scuba tank

ETA: Post #14 in this thread refers to the Russian titanium cylinders that I refer to above!

rx7diver

 

[Gone for diving]

I remember something about the Soviet Union using SS tanks..... but they where weld... and where not legal in north America... I could be wrong about being SS though?

 

[evandroairton]

I remember reading in (the defunct?) Underwater USA magazine/newspaper in the early 1990's about titanium scuba cylinders. I think someone was importing them from the Soviet Union (or contemplating importing them). I think I recall that two sizes were described, the smaller cylinder having dimensions similar to the old Scubapro "Slimline" 63 or 66. I made a note on the cylinder spec page of my Cave Diving Manual, I think, because of my "forever" interest in smaller, lighter, and simpler scuba. I'll look this up when I return home this evening.

rx7diver

The Cousteau team used Ti tanks, 4500 psi during the "rediscovery the world" series, 4 smal (3 main, one reserve) within a compact silver shell, replacing the previous Raid, but they have issues, AFAIK, with integrity with far less compression cicles than expected