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Aluminum corrosions tends to be self-limiting, but aluminum cylinders are awfully bouyant nearing empty.
Steel tanks corrode easily, are more expensive, are far more costly but are available in a larger variety of sizes.
So which do you prefer and why?
Babe,Quote:
Originally Posted by iDiveChick
This might help you.
Choosing a scuba cylinder today is easier than it has ever been. With more than 100 products available there is a cylinder for everyone's needs. Bouyancy charachteristics are easily understood as are all the other specs.
The "standard" aluminum 80 has been around for more than 20 years and is the most manufactured product. Between Luxfer and Catalina cylinder companies they make a combined 125-130,000 units a year. BUT that does not mean its the best tank for all people. It's just a good general tank that does not allow you to sink like a rock and will help you get up when you run out of air. (for single tankers) It's bouyancy when empty is only 4 lbs positive. not all that much.
Aluminum cylinders today are well made and will last a very long time so long as you care for them. Just like your BMW if you take care it will last a while if you dont it will get nasty.
Aluminum Cylinders are available in 4 cuft - 100 cuft sizes. With a large selection of ponys. Popular sizes are 50, 63, and 80 cuft.
Steel cylinders today are made by the following companies for US distribution. Faber, Pressed Steel, Asahi, and Worthington. All totaled they may be responsible for 100,000 cylinders a year with Faber being the largest seller.
Faber cylinders are chrome molybedenum steel that is spray galvanized, epoxy painted and finished with a clear poly-urethane coating. These cylinders will last forever. I have some now close to 20 years with No rust and no corrosion. Faber has the widest selection of cylinders from 12 cuft to 149 cuft. 19 sizes are available.
Pressed Steel makes a hot dipped galvanized cylinder. This product is a "metal finish" that will resist corrosion. However because of the hot-dip galavanization process it is more suseptible to internal flash rust at manufacture. This is not a problem so long as the cylinder is cared for.
Sizes are 45 cuft - 130 cuft -- 9 sizes available.
Asahi makes a spun steel tank that is triple coated like the Faber but in limited sizes 80, 100, 120 cuft 3 sizes available.
Worthington makes a cylinder similar in nature to the PST tanks. Orignial Worthingtons were painted now they are hot dip galvanized. 13 cuft - 130 cuft --- 14 sizes are available.
The key to taking care of cylinders is to only have them dry slow filled, and to only fill them with purified clean dry air or appropriate mixes gases. Any water that gets into a cylinder will begin to immediately damage it.
As to cost on products. The aluminum 80 today is selling in the 155-165 price range with a proper valve. A typical aluminum cylinder will go out of service in about 15 years, they are also more suspeptible to failing hydro because they are not as "elastic" as a steel cylinder is.
A corresponding steel cylinder in the 80-100 cuft range is about $100 more. BUT will require 10 lbs less balast. so you save $50 there on less lead. So the Steel tank is net about $50 more.
As aluminum and steel prices soar you can expect tank prices to go up another 20% in 2008.
Choosing a cylinder size is critical to your diving.
Got a tank question ? Just ping me ..........
Cheers
Aluminum, because that's what I got for my birthday. :DQuote:
Originally Posted by iDiveChick
have both but steel is a lot nicer. I have an extremely old steel 72, it's first hydro was in 1963 and it just passed hydro and vip with no problems didn't even need to get cleaned - had no rust.
Should i throw a spanner in the works and say Inconel?
Just a dream at the moment but hopefully not for too much longer.
Matt
I have both but for the capacity I find the steel tanks to be smaller in size, and the few extra lbs of neg bouyancy is nice.
i would dive with the aluminium tank, but then i'd just float. so i use the steel tanks.
It depends on the dive My cave dives are done with steels. My Intermediate ocean dives are done with double Al. 80's. Deep and/or long ocean dives are with double steel 95's (am thinking of upgrading to 104's or 119's) All stages and deco bottles are Al 80's or 40's depending on the gas requirerment. The argon bottle is Al 6 or 13 cu.ft., again depending on the duration of the planned dive. For the shallow ocean dives, I still like the single steel 72, in very warm water---of course.
My first set of double's were a set of steel 72's. This was a good intro into the diving with doubles. The single 95(steel) is also a good intro into the "more gas required dives" while still using the BC single reg set-ups.
So My answer? IT ALL DEPENDS
I doubled up a set of PST steel 130's ... had to rig up an eye where the crane could attach to lift me into the water ... ha ha Kidding. They actually aren't too bad, and it sure is nice having all that gas with you ...
Ron, you're just too cute :D 130's though, wow- I wouldn't be able to stand up with those things on my back...Quote:
Originally Posted by seasnake
But as for me, steel all the way. I do not like Aluminum, except for my stages..
Im steel all the way for everything but have just started thinking more towards alis for stages. Everythings getting too heavy so a bit of extra bouyancy out of tanks wouldnt go astray.
Matt
Depending on how much , when , were, and how you dive they both have good and bads.
I would say steel if you are only going to own 2 or 4 tanks.
Please whatever you use keep them inspected and clean, if you are using them a lot , like each weekend for a wile get them looked at each 6 mo.
The 1 year vip that most think is bs can be even to long.
I worked at dive shops and have see 1000s of tanks and even divers get sick from off sight fills at places we thought were OK to use.
Most shops will vip for 5-10 bucks less than what you paid for lunch.
And some will even check at 6 mos for free if you are using the shop for gear and travel. If not find a good shop, it only takes 2 min tops for a good tech to do you this service.
Know your air supply,its your life we are talking about.
We can live for WEEKS without food,DAYS without water,and only a moment without AIR.
Why bother with all that weight when you can fill an 85 to 4k and have a lightweight 120:eek:Quote:
Originally Posted by seasnake
As others have said, the decision between using steel and AL cylinders comes down to the dive. Most dives I use steel for my primary cylinders and AL for stages and/or deco bottles. For sumps I will use whatever I can get someone to help me carry to the water; that may be AL 40's or lp 45' or even lp 72's or perhaps AL 80's or lp 85's. It all depends on what is being planned and the conditions of getting to and from the water's edge.
I like steel...it takes some lead out of the BC which is nice when I'm diving the 7mm.
I'm not one to overfill my tanks.Quote:
Originally Posted by BamaCaveDiver
Over filled 130's... Over kill, but feels good to know there's air on your
back at depth.. What was that loud bang I heard and that roaring sound
I'm hearing?
I don't overfill, I always stop at 4000psi :pQuote:
Originally Posted by seasnake
I vote for Aluminium .... less weight for my back
RSL
That really depends upon the cylinder. AL being a softer metal requires thicker cylinder walls than steel, so not all AL cylinders are significantly less in weight than the AL.Quote:
Originally Posted by redsealovers
I will interject here that although I dive steel and Aluminums, depending on the dive and application, I WILL NEVER STRAP ON A AL 100!!!!!!! This tank has got to be the worst tank ever manufactured. It is nothing more than a balloon. I HATE that tank!!!!
Quote:
Originally Posted by amtrosie
I had two of those that I finally managed to swap for AL 80's about a year back; I swear I could not price them low enough to find a buyer for a couple of years! They make good ow cylinders for large air hogs, but that is about it. Way too heavy when full and way too floaty when near empty.
I own 2 12L fabers doubled up. 2 13.6L Asahi's as singles and a 8.3L Catalina stage that I just brought.
Tanks in NZ as so expencive. I supose its got to do with increased shipping prices. My 8.3L cost me $450nz ($300US) O2 cleaned with Nitrox stickers.
My fabers cost me $370 each without valves which was a real bargin. Normaly pay about $500 with valve.
i dive with both types, prefer? depends on the dive. Steel does last longer though.
I own steel HP100's and couldn't be happier with them. The relatively small size and negative bouyancy are nice. Naturally when I travel to faraway places I have to dive what's on the boat, and that's usually AL80's.
Mountain Dog
The Aluminum 100's suck for one reason they fill at 3300 psi. So on a boat you get 3000 that cools to 2850psa you have a huge 80 anyway. I have both, but really like my LP95 and my LP120 both steel for the longer times I might need to get the "Shot". Aluminum 80's are great for cold water, you don't have to stay down as long. I have posted this before, but LP is the way to go because you can get a good fill anywhere.
Bama, 4000 isn't an over fill at all!;) 4100 maybe! Right?
I have everything you might want to know about Tanks in one place at our site feel free to us it as a resource!
http://www.twotankedproductions.com/...f/tanksqa.html
I own HP 100's and love then too.. BUT Papa brings up good pointsQuote:
Originally Posted by Mountain Dog
I own an ALUM 100 and 80's and LP 108's and HP 100's ... As papa said, the HP's are hard toQuote:
Originally Posted by papa
get a good fill.. The LP are easy to get a good fill.
If I had to choose my tanks over again, I would go for the LP98's and crank them up to 2449lbs... (lol).
That is what Cavers do all day long! Twin 108's to 3800psi almost 300 cubic feet of air! Or better yet 300 cubic feet of 36%!;)Quote:
Originally Posted by lars2923
Yea, I didn't want to write that... but your' right...
twin LP 108's over filled, what else can you do... Go rebreather or something?
My favorite all time tank shore or boat is the LP steel 95!
http://twotankedproductions.com/imag...e_Peace_08.jpg
Fit, buoyancy, just enough extra air in cold water! LOL I wish Live a boards would use them! You would almost not need any additional wight! Maybe 8 to 10lbs and your good to go!
I believe Nekton uses them...Quote:
Originally Posted by Papa Bear
Best tank I have ever used was a HP100. Getting to remove 6 pounds of lead from the weight belt and having 23CF more air at the same time is great compared to the typical AL80. Too bad the friend that lent it to me wouldn't let me keep it. :(
HP 100's are nice but you should be using DIN with them, NOT saying that you have to, but I know a few people that the o-ring for the yolk plug slid out. Only one person using it, but quite a few when getting them filled on a yolk fill whip. The LP 95 is pretty much the same height but just fatter, also with a boat fill of around 3k it's WAY over a 100.
I really like steel 72's! I had an alum back in 1975 and it just didn't last. My oldest steels are a set of 38's that were made on 4/1943 and 5/1943 and they just passed hydro! If I went with HP it would have to be steel also. Yes they are costly, but they will last a lifetime. I've heard of welding cylinders that were from the turn of the 20th century still in use. Steel, get you some.:D Tim
For example: For Doubles, Steel 108's.
For a Single tank, I use LP 95 Steel.
For the OW students, AL 80
I use to own 100's but they were hard to fill to working
pressure 3442.. So I went to LP 95's with a working
pressure of 2400, which is easy to fill to that pressure if
the shop is filling AL80's to 3000... Any pressure over 2400
is a bonus...
Keep track of your SAC equivalent for each dive to help you
determine the amount of gas for the time and depth you like
to dive to determine the amount of gas to carry, hense the
cylinder you require to hold that volume with reserve to spare.
http://www.dive-logs.com/infosac.jsp
http://D*D.com/article/make_the_most_of_every_tank
http://home.flash.net/~table/gasses/sac.htm
Lars
I use steel tanks for back gas and ali tanks for deco/bailout gases. In the UK steel cylinders are cheaper than Ali.
I have a pair of steel 300 bar 12L, they're heavy :) I need the Ali deco cylinders to combat them :D
Here steel tanks are twice the cost of aluminum.