Steel 72s v. Aluminum 80s

[sarita75]

Good afternoon all. I have an opportunity to buy either 2 steel 72s or 2 aluminum 80s. I have actually never dived (dove?) with steel tanks and am not sure about the capacity differences, etc. My main concern is that, when I was using alum 63s I was using more air than my husband, so 80s are better. Is there much difference between the 2 (steel v. alum)?

Thanks in advance!

 

[mike_s]

The difference is volume, metal type, and bouyancy based on the metal.

The steel tanks will be slighly more negative bouyant in water, which means you'll be able to wear slightly less weight on your weight belt. They will also be more compact in size for the same pressure category as the steel tank can hold more air with thinner walls.

Volume different is this. The steel 72 is actually something like 67 cubic feed of air at 2250psi. The AL80 is actually 77cf of air at 3000psi.


Most folks that dive alot prefer a steel tank because of its weight characteristics in water... however, most folks don't prefer a smaller tank unless they are a smaller body person and have much smaller air consumption.

hope that helps some to base your decision on.

since you're using more air than your husband, you might need the bigger tank as your selection indicator.

 

[Stu S.]

You need less lead on your belt with the steel. Steel 72's were the standard tank until about 1980, and aluminum took over. A brand new steel 72 is unusual, so you might be dealing with all the advantages and disadvantages of an old cylinder.

It would be easy to try an aluminum 80. Although it is actually 77 cu. ft. It is the most common rental tank. There is also a new steel 77 that may be a good choice. Dive Sports had them listed on-line.

Good luck!

 

[Tom Smedley]

You didn't specify if the steel 72's you are looking at are high pressure or low pressure. I have both and love them both but the high pressure tanks are shorter and heavier than the low pressure tanks. My dive partner uses hp 72's and it's hard to get her to change to anything else.

 

[garyfotodiver]

There are new steel LP 77s available. I bought two and like them.

No longer will I search for used steel LP 72s. They are more trouble than they are worth.

 

[mike_s]

considering a new AL80 costs $180 on average, I'd go with the LP77's for $199 if buying a new tank of that size range. (and go ahead and get the Thermo Pro Valve)

 

[Luis H]

There are new steel LP 77s available. I bought two and like them.

No longer will I search for used steel LP 72s. They are more trouble than they are worth.

That is funny, I have 11 of them now and have owned many more, and never had any trouble. But I am glad there are people that don't like them, it keeps the price down.

 

[garyfotodiver]

That is funny, I have 11 of them now and have owned many more, and never had any trouble. But I am glad there are people that don't like them, it keeps the price down.

I like them; I learned on them. But I find that with the cost, plus a hydro, plus gaining +/-10cf of air with a steel 77, it is not worth the effort to maintain steel 72s.

Just my opinion. Nowhere do I mention that everyone else should follow my opinion, nor that it is the ONLY opinion.

See below.

 

[mike_s]

Originally Posted by garyfotodiver
There are new steel LP 77s available. I bought two and like them.

No longer will I search for used steel LP 72s. They are more trouble than they are worth

That is funny, I have 11 of them now and have owned many more, and never had any trouble. But I am glad there are people that don't like them, it keeps the price down.

I've kinda got to agree with garyfotodiver.

While I think the steel 72 is a great tank, for what it cost me the last time I bought two of them, I could have bought new tanks. (I had to pay for hydro, visual, air fills, then found out the valves leaked, new valves, new air fills, repeat again with the 2nd tank on new valves and leaked fills, etc. It was just a hassle to get to the dive site only to have found out you had a leaky valve and no air in the tank).

now if you can get one for a good price with good valves, they are a great tank, especially for a smaller frame (body) diver with lower air consumption.

 

[DA Aquamaster]

The generic (and no longer produced) Steel 72 held 71.2 cu ft at the plus rated fill of 2475 psi and 64.7 cu ft at 2250 psi.

They are about 4 lbs more negative than an AL 80 when empty and they are about 2 lbs lighter, so you can drop 4 lbs of lead and carry 2 lbs less tank weight saving you about 6 lbs going up the ladder after the dive.

The Faber 72 is a 3000 psi service tank that holds 72 cu feet at a plus rated 3300 psi and 65.5 psi at 3000 psi. It is about 8.5 lbs when full making it about 7 lbs more negative than an AL 80 and about 3 lbs more negative than a generic Steel 72. The nice part about a Faber 72 is that it is about 6 inches shorter than an AL 80 and about 4 inches shorter than a steel 72 making it a nice choice for shorter divers.

The economics of buying a used steel 72 depends a lot on whether the hydro and VIP are current and on the cost of a hydro if they are not. Many also come with older J valves and many divers prefer to upgrade them to K or DIN/K valves. But if you can get a tank with a recent hydro for $100 with a decent K-valve or DIN/K valve it is a great deal. If you get the same tank for $100 and have to add $40 for a new valve it is an ok deal. If you have to add a new $40 valve plus pay for a new hydro at $15.00 to $25.00, a new AL80 looks very attractive.

I own about 15 Steel 72's and some were great deals while others needed a lot of upgrading valve wise. Now that I have a compressor I seem to use a lot fewer of them and will probably sell some off.