Help, 100 cf Aluminum tank???

[Boogie711]

The AL's have the same bouyancy swing as steel. Air is air - whether it's in Aluminum or steel, when you remove the air, the amount of weight removed will be the same.

The difference is that for more steel tanks, they start negative and end negative. IE - a Steel 80 will be 7 lbs negative full, and 1 lb negative empty. But an Aluminum 80 starts 2 lbs negative, and swings to 4 lbs positive. But it's still 6 lbs of 'swing.'

Outlaw Aggie - yes, a LP tank will often be somewhat bigger, but not necessarily. The reason is that a steel tank is much thinner than the walls of an aluminum tank, and they can therefore in fact even be smaller.

I would recommend a PST E7-100. It's smaller and lighter than an AL80, but holds an extra 20 cf of air at it's rated pressure (3442 psi) and will still accomodate a Yoke valve, if needed. At lower pressures (2640 psi) it still holds 80 cf, even though it's smaller than an AL80.

(note - DIN is awesome, and I don't recommend a Yoke valve even for Caribbean reef diving, but that's another issue.)

 

[Spectre]

Technically an AL 100 is 22.6 cuft more than an AL 80 [assuming Catalina].

A steel tank of comparable dimensions will be able to hold more gas at the same working pressure, because the walls of the tank are thinner.

AL100s are decent tanks; but they are -big-. They are comparible in size to the old PST 104s, but those hold 104 cuft at 2640, rather than 100 cuft at 3300 psi. The PST E8-130s are a little smaller, a little lighter, and hold more gas.