Aluminum vs Steel? Pressure

[krisdahl]

I read a post somewhere talking about how most NW divers prefer steel tanks. Is it just the higher pressure or what is the advantages?

I'm new at this and looking to buy my first setup.

[Dashrynn]

I read a post somewhere talking about how most NW divers prefer steel tanks. Is it just the higher pressure or what is the advantages?

I'm new at this and looking to buy my first setup.

my personal opinion which is null compared to most here, but it would be steel has way better buoyancy characteristics. I have 2 steel hp100s 1 steel lp95 and 2 al80's and i prefer my hp100 over my lp95 any day. Now I haven't tried my al80s in a long time but i always had to put a little extra weight when i used my al80 so i wouldn't "cork" but that being said i have corked at 5 fsw using a steel tank too. Even though steel has better buoyancy as most say they still loose there weight when depleted to 500 psi.

Another thing to consider is high pressure to low pressure, some shops cannot fully fill a hp100 so you end up with 3200 psi instead of 3400 which is 3 cubic feet for every 100 psi so in the end you loose about 6 cubic feet in your tank resulting in the equivalent of a lp95, but heres were it becomes a preference even more than steel vs al or hp vs lp....i love the hell out of my hp100's and i would rather be short a few 100 psi than to give up my hp100 for a lp95....

thats my 2 psi and im sticking to it

[Geek]

It's a combo of things, steel tanks are heavier, taking some lead off your belt.. you can get more cubic ft in a smaller tank and steel tanks have better bouyancy charicteristics when they run low... to name a few off the top of my head..A lot of divers I know have Low presure steel tanks... yea, what he said...

[psundquist]

Simply put, Steel tanks are just magical compared to Aluminum. Due to the buoyancy characteristics of a HP 100 vs. AL 80 you actually need less weight overall for diving. These characteristics are common to all steel tanks. This is important for dry suit divers since you need more lead to sink.

You can compare all of the popular tanks at: http://www.huronscuba.com/equipment/scu ... ation.html or look up the characteristics at: http://www.xsscuba.com/products.html

Plus the corking just sucks with the AL80 in a dry suit.

[fmerkel]

In addition 100's (or more) are kind of the 'standard' minimum for serious NW divers. After awhile you just can't keep up with an 80 unless you are small or incredible with air consumption. That is not a small thing after awhile.

Aluminum 80 > steel HP 100 = lose 5-6# off your weight belt AND have 20% more air. What's not to like?

Drawbacks - costs more and it can rust (mostly internally) if you aren't careful. Not an issue with reasonable precautions.

[Gooch]

Steel is the way to go, but aluminum is cheaper- both hold air so we can see cool stuff- 'nuff said

[dwashbur]

I prefer steel because its weight stays more or less constant during a dive. With aluminum you have to wear more weight, partly because the tank itself is lighter, but mostly because as you breathe down the tank, it gets lighter and your buoyancy suffers. Plenty of people can get used to that; I'm not one of them. I'd suggest you find a way to try both for several dives and decide which is best for you.

[Tangfish]

krisdahl, I just emailed you a spreadsheet that details the differences between various tank types and sizes. I hope that helps better illustrate the tradeoffs.

Cheers,

Calvin

[LCF]

I prefer steel because its weight stays more or less constant during a dive. With aluminum you have to wear more weight, partly because the tank itself is lighter, but mostly because as you breathe down the tank, it gets lighter and your buoyancy suffers.

I believe your perception is this because the steel tanks remain negative throughout the dive. But the swing is the same; if you exhaust five pounds of air into the water, you are five pounds lighter, no matter what the material of your tank.

To the OP -- steel makes sense in Puget Sound. If you compare a steel tank and a aluminum tank with the same gas capacity, the aluminum tank will be larger and weigh more on land, but it will not be as negative in the water, and it will therefore require you to wear more lead ballast, so you end up carting around more weight overall. Aluminum 80s also end up becoming light at the butt end as they empty, which changes your balance in the water.

[Norris]

Steel has a neat color

[krisdahl]

To the OP -- steel makes sense in Puget Sound. If you compare a steel tank and a aluminum tank with the same gas capacity, the aluminum tank will be larger and weigh more on land, but it will not be as negative in the water, and it will therefore require you to wear more lead ballast, so you end up carting around more weight overall. Aluminum 80s also end up becoming light at the butt end as they empty, which changes your balance in the water.

The aluminum tanks are *heavier*? I thought that they'd be lighter, which is why when they get empty they become more buoyant. I suppose if they are larger as well for the same amount of air, that would make them more bouyant.

Running two 80's is probably worst idea--heavier but has an even bigger buoyancy swing from full to empty?

-k

[LCF]

Remember that weight is one thing in air, but density is more important in the water. Aluminum is less dense, so it's more buoyant, and because the tanks are larger, they displace more water.

Double 80's, paradoxically, are not as annoying as single 80's, because the bands and manifold make them come out pretty close to neutral. They're very nice doubles for warm water, especially warm fresh water.

[ArcticDiver]

Weight is weight so whether you wear it on your belt or in your gas supply is a matter of personal preference and diving environment.

Weight swing as gas is consumed is another matter. It must be compensated for. How is another matter.

To me since each have pluses and minuses the steel vs aluminum argument is greatly overblown.Pick what matches your budget and diving style and learn to use it.

[LCF]

Weight is weight so whether you wear it on your belt or in your gas supply is a matter of personal preference and diving environment.

Not quite so . . .

Al 80 31.4 lbs empty; 4.4 pounds positive = 35.8 pounds of weight
Faber FX80 28.6 lbs empty; 1.74 pounds negative. So the tank is 3 pounds lighter, and I need to carry 6 lbs less lead.

Almost 9 pounds less total weight on land for the steel tank. That's enough to make a difference to me!

[ArcticDiver]

And that is the key; looking at your budget, availability and deciding what is best for each individual. For many on land performance may not be important. Budget or availability may be THE deciding factor.

Personally, I'd not fault any decision as long as it was reasoned and considered all known factors. After all, isn't that what we've all been taught and teach others?