72 cf aluminum

[ReefHugger]

Can anyone tell me where I can get 72 cf aluminium tanks?

Seems as if the manufacturers have not only discontinued this size but also the 67 cf. - so now, either 63 or 80 cf. only in aluminum (steel defeats the weight advantage).

Maybe, we should start a lobby here!

 

[captain]

72 cu/ft aluminum 6.9D tanks disappeared 30 years ago. They were way too buoyant. What weight advantage. Why not steel. The old steel 72 had perfect buoyancy and are easy to find.

 

[Scuba-Stu]

Can anyone tell me where I can get 72 cf aluminium tanks?

Seems as if the manufacturers have not only discontinued this size but also the 67 cf. - so now, either 63 or 80 cf. only in aluminum (steel defeats the weight advantage).

Maybe, we should start a lobby here!

CylTec makes these tanks.

You can find them here:

https://www.diverightinscuba.com/catalog/cyltecaluminum72-p-2487.html

 

[Gilldiver]

72 cu/ft aluminum 6.9D tanks disappeared 30 years ago. They were way too buoyant. What weight advantage. Why not steel. The old steel 72 had perfect buoyancy and are easy to find.

There are a few cavers who like them as stage bottles.

I am trading a aluminum 72 I found in the scrap pile at my town dump a few years ago for a nice steel 72. I had been using it as a knock around tank for filling ballons, tires, pool toys etc. Full with a regulator on it, it wants to float in a pool.

 

[DA Aquamaster]

I just bought one a couple months ago for use as a stage and as a buddy bottle when on a two person team.

Hy-Mark cylinders makes them. My understanding is that Mark from VA scuba approached Hy-Mark about copying the old AL 72 and that is pretty much what Hy-Mark did but with a bit more metal around the neck.

They do make great bailout bottles for rebreather divers as they are narrower than an AL 80 or AL 63, but carry a lot more useful gas than an AL 40 or AL 50.

They are also neutral with a reg attached and about 500 psi in the tank, so they don't have that tendency to float up behind you when near empty and unlike an AL 80 they do not result in you needing to compensate for 4 lbs of positive bouynacy per stage at the end of the dive when you are already low on backgas and light anyway, all of which makes them great stages.

 

[rstofer]

72 cu/ft aluminum 6.9D tanks disappeared 30 years ago. They were way too buoyant. What weight advantage. Why not steel. The old steel 72 had perfect buoyancy and are easy to find.

I didn't realize LP 72s were held in such high regard. Now that I have one, I am beginning to understand. I think I'm in the market for another couple of them.

Richard

 

[SparticleBrane]

...that is pretty much what Hy-Mark did but with a bit more metal around the neck.

I noticed that when I was looking at some comparison shots between Luxfer Al40s and Cyl-Tec Al40s on DiveGearExpress.


Specifically, look at this shot -- anyone think this might help prevent possible issues with neck cracking? Not being an engineer I wouldn't know, but it seems plausible at least.

I have heard from several people that the Cyl-Tec cylinders have essentially the same weight/balance/buoyancy characteristics as Luxfer cylinders for use as stage/deco bottles, which is good news since Luxfer is leaving the scuba market.

 

[captain]

Years ago 70's the first time I tried an aluminum 72 I was used to using about 4 pounds of lead with no wet suit and a steel 72 in saltwater. I put on the same lead with the aluminum 72 and couldn't even swim down. My first and last time with one.

 

[ReefHugger]

Thanks for your responses, esp. Scuba-stu and DA Aquamaster (any link for HY-Mark?).

To Captain - the wgt I referred to, was the physical wgt of the tank. The al 72's are a little lighter and IMO the best compromise of vol/wgt especially for women (general handling, carrying and hauling around). Would have preferred them to be 2" shorter, but as I said - compromise.

 

[DA Aquamaster]

Years ago 70's the first time I tried an aluminum 72 I was used to using about 4 pounds of lead with no wet suit and a steel 72 in saltwater. I put on the same lead with the aluminum 72 and couldn't even swim down. My first and last time with one.

The Hy-Mark 72s are neutral in fresh water with a first and second stage attached at about 500 psi. So they are in effect about 3 lbs less buoyant than an AL 80.

They are also about 3 lbs lighter compared to an AL 80. When you compare numbers it offers many of the advantages of a steel 72 with a bit less negative buoyancy, about a pound less weight but a bit more height.

In terms of the numbers the differences do not sound like much but I absolutely hate using a steel 72 as a stage while the AL72 feels perfect.