Aluminum VS Steel

[louisianadiver]

I am currently in the market for a tank. Having been to the LDS and talking to friends I am totally confused. One says Aluminum is better because theyare cheaper and don't corrode as fast as steel does, the other says Steel because of bouyance and size. Could someone shed some light on this for me?

Keep in mind that the AL80 is standard on most dive charters, and most boats will be set up to carry them if you bring your own tank(s). Steel tanks usually have a wider girth and won't fit into carriers designed for AL80s, and many captains won't allow steel tanks aboard because they can't be properly stowed. -Clay

 

[Charlie99]

Keep in mind that the AL80 is standard on most dive charters, and most boats will be set up to carry them if you bring your own tank(s). Steel tanks usually have a wider girth and won't fit into carriers designed for AL80s, and many captains won't allow steel tanks aboard because they can't be properly stowed. -Clay

Perhaps true about LP tanks, but there are quite a few steel tanks that have the same 7.25" diameter as the AL80.

In particular, the 3500psi HP100 is the same 7.25" diameter and the height is about 2" shorter, so AL80 tank racks, bungies, etc. should work. The internal volume is greater than an AL80, so even with a 3000psi fill, the HP100 will have greater than 85 cu ft.

Weight: AL80 empty is 31.7 pounds, with 4.4 pound positive buoyancy, for a total of 36 pounds. An empty HP80 is 27 pounds, with -1 pound buoyancy, for a total of 26 pounds. Your total dive gear weight will be 10 pounds less using the HP80. Or you can go with the 33 pound HP100, neutral when empty, and your total weight will still be less than with the AL80.

If you are buying tanks, I strongly recommend that you go with DIN for the tank valves and your regulator.

 

[hantzu701]

Tank selection depends on the kind of diving that you do.

I have buddies who use a small 19ft boat for diving in Lake Michigan. In order to get into the boat, they have to remove their weights and BCD/tank in the water before climbing back on board. As a result, they dive almost exclusively with a wet suit and use AL80's and AL100's to reduce the weight that they haul back on board. Cost is another issue. For 2 new steel tanks ($700), you can buy ~ six used AL80 tanks. For frequent divers, it's much easier to drop six AL80's to the shop to get fills once every few weeks rather than going every time you need a fill. If an AL80 fails, then they're cheaper to replace. If you tend to be a warm water diver, then you'll see AL80's on your dive trips. The rig you dive with at home will be the same that you use on trips.

HOWEVER, I like steel tanks with my drysuit. I dive in cold water.

 

[Boogie711]

Steel is heavier on land though, so there is a trade-off there.

Not really.

An E7-100 is smaller and lighter than an AL80. It's 7.3" diameter, so it fits in an AL80 tank rack. It's negative at the end of the dive, so you can take 4-5 lbs off your weightbelt. And it holds an extra 23 feet of gas over an Al80.

 

[MyDiveLog]

Benefits of Aluminum vs steel:
- Biggest is cost ... you can almost always find one for near $100, which is about what the tank & valve costs the shop. A steel tank will cost 2x - 3x as much.

- The AL80 is nearly ubiquituous ... boats are designed, most often, to hold them. My Steel 80 almost never fits, although I do mostly beach diving anyway. Nearly all boat compressors fill only to 3000 PSI ... a "full" tank with an AL80, but a "light" fill for an HP Steel tank.

- They don't rust like steel .. read the latest issue of "Lessons for Life" in Rodale's and you'll see a real-life example of this hazard. Having said this, it should NEVER happen from purposefully running down all your air.

Benefits of Steel vs Aluminum:
- Steel is stronger than Aluminum, so they typically hold more air in less space (i.e. higher pressure). That can be a + for smaller folks, for whom an AL80 would hang down well past their butt.
- Steel tanks are stronger than AL tanks ... they hold up a bit more to abuses like banging, etc. The crimping process which forms the necks of AL tanks also tends to create a potential weak spot ... if the AL tanks fail a visual, this is most often where it occurs. A VIP inspection for an AL tank, because of this, includes an electronic check for cracks at the threads.
- Bouyancy characteristics (probably the biggest +). An AL80 tank is 2 lbs negative at the beginning of a dive but 4 lbs positive at te end. Contrast this with a steel tank, which is typically neutral (or even negative) at the end of the dive. This means that I have to add 6 lbs to my weight pockets when I dive with an AL80 vs my steel 80.

My recommendation: There's a new LP steel tank on the market that seems to offer the best of AL and Steel. It has all the bouyancy characteristics of steel, but is the size of an AL80. Because the fill pressure is 2475 PSI, you'll get great (sometimes TOO great) fills when boat diving. It'll fit into the standard AL80 tank recepticles.

 

[Kaiser]

First off, thanks to everybody responding to my question. Form what I gathered, the most cost effective tank to buy would be a aluminum tank that remains negativly bouyant. I've seen such an animal at diversdirect. It's about 20 bucks more than the standard Al80. Who carries the LP steel tanks?

 

[TwoTanks]

I dive one of these, but seem to run out of NDL all the time. Pretty difficult to handle out off the water..........

http://stainlesssteeltanks.info/

Your using it wrong....

You are supposed to be in the tank. :11:

TT

 

[Don Burke]

Form what I gathered, the most cost effective tank to buy would be a aluminum tank that remains negativly bouyant.

Four pounds of lead is cheaper than the extra cost of the neutral tank.

On the subject of steel, if you spread the extra cost of steel over a twenty year period, the extra cost is only about ten dollars or so a year. If you live in an area where all aluminum tanks are required to have a visual plus, steel may work out cheaper in the long run.

 

[Scubamedicjoe]

Alum is cheaper but in long run for money steel way to go. But keep in mind allot depends on what type of furture diving you going to do.
Another thing to consider is they have neutral alum 80's now not much more than reg 80's
I use steel HP 100's and not a problem with fills the shops I use are good people and not a problem.