Which short steel tank??? help!

[Scubakevdm]

Put another way, density is simply a function of mass and volume. Volume doesn't actually matter, it's the mass that determines buoyancy. When you take 80 cf of air out of a tank - any tank - you reduce its mass (and therefore weight) by the same amount.

Density determines bouyancy. At least it used to.

 

[Eris Lucan7*]

Highfine *Ö.Ö*

Take a alu no steel , i am useing 12 liter high singel and doubel alutanks at all.

 

[Scubakevdm]

Right. It's the, "which weighs more, a ton of lead or a ton of feathers?" In this case it's, "which weighs more, 80cft of air or 80cft of air?"

Joe

In this case its "Which would float, a ton lead or a ton of feathers?" Weight is what complicates it for many people.

 

[Dan Gibson]

No, displaced volume determines the buoyant force. Although it's also nice to know the properties of the specific liquid you are placing an object in.

Density determines bouyancy. At least it used to.

 

[Dan Gibson]

Most of the published lists are not correct. Some are fairly accurate and some are not even close.

Whatever produces the swing, Table 1, "Sample List of Avialable Scuba Cylinders" in the PST dealer book lists the bouyancy characteristics of a variety of tanks. This table lists an LP 80 (78 cu ft. @ 2640 psi) and an HP 80 (80 cu ft @ 3500 psi).

Saltwater bouyancy for the LP 80.... 0.7 lbs empty..... -4.7 lbs full. Swing = 5.4 lbs.

Saltwater buoyancy for the HP 80... -7.3 lbs empty.... -13.2 lbs full. Swing = 5.9 lbs.

That's a half pound less. Granted, the LP tank has has 2 cu ft. less volume, but it just doesn't seem like 2.5% of the volume is going to account for 10 percent of the swing. Anyway, like I said regardless the reason why the LP tank swings less, at least according to PST.

 

[Dan Gibson]

I'll bet if you pack the feathers into a small enough volume, you can get it to sink. I'm pretty sure one can also get lead to float. I know people have done it with concrete and it has a higher density than water. It's all about displacment.

In this case its "Which would float, a ton lead or a ton of feathers?" Weight is what complicates it for many people.

 

[The Kraken]

Highfine *Ö.Ö*

Take a alu no steel , i am useing 12 liter high singel and doubel alutanks at all.

Translation, please . . . ???

 

[ChrisA]

Not that I'm getting one TODAY! (that would be because I got a BC today!)... but hopefully in the near future I will be considering a tank. I would like steel (need the weight) and I really want one as short as possible, while still holding a comparable (sp?) amount of air to a "normal" tank. Are most rentals A80??? I do'nt want to run out of air before anyone else, just looking for something to not bonk me in the back of the head! Lots of sites don't seem to list actual dimensions of tanks, just air ratings. Thanks for any help!

Here is everything you would need to know....
http://www.huronscuba.com/gear/cylinders.htm

I have three steel tanks. All are shorter then the AL80. The sizes are 95, 80 and 72.
All mine at LP with service pressures between 2640 and 2250. The HP tanks are
nice but check the valve type and the availability of HP fills on boats.

 

[Scubakevdm]

Edited by owner in an effort to make a more pleasant community.

Yes, it (buoyancy) has do do with displacement, but mass is a part of it too.

 

[The Kraken]

Actually, I've been following this with some great deal of interest.
I'm looking at getting into doubles this spring/summer and want to go ahead and get some tanks that I can double up.
Needless to say, the confusion now with the newly introduced steel tanks from PST makes the choices much more difficult.