HP Steel Pony

[hypertech]

I've been thinking about getting a pony tank but it seems like they are only made in aluminum. Wouldn't HP steel make a lot of sense? It would fit more air in a smaller volume.

 

[OldNSalty]

I've seen some steel pony tanks. They are not significantly smaller but they are heavier with worse characteristics then their Al counter parts. I understand your thinking, I had the same idea and was surprised to find out that there was no great gain. In fact, after looking at the 2, the Al was the better tank.

 

[hypertech]

I don't understand. How could they have worse characteristics? A certain amount of air has the same weight whether it is in an aluminum or steel tank. Are you referring to them being more negative? Why is that worse? At most they could only be a pound or two more dry weight. I can't see that being an issue.

 

[OldNSalty]

My bad, it was a LP steel. Here is a chart.

Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

Al-little wider but a little shorter vs Steel-skinner but taller.
Buoyancy full was a little heavier for the steel tank.

I dive in warm water so I like stuff to be closer to neutral and I was thinking that a steel 19 might be as small as an Al 13 but it isn't.

I'm not sure about a HP pony. I guess if anyone made them they would be smaller for a given size.

 

[OldNSalty]

Here is a HP 23.

Faber 23 Cubic Foot High Pressure Steel Pony Bottle Tank FX Series FX23DV with reviews at scuba.com

little more air then an Al 19-little taller physically as well.

 

[hypertech]

Hey, thanks. I wonder why I didn't find that before. Most of the guys around here are using AL30's and 40s for ponys. I'd like something smaller. I've done a little of the rock bottom math, but any dive I can't get out of on 23cf is one I'm not trained to do or interested in anyway.

 

[a22shady]

Depending on the size Luxfer Al 30-40 are best as they lie better in the water more even and are close to being neutral

 

[elan]

On a practical note the HP pony will have less capacity. It is very difficult to top it up from your main cylinders if necessary in the field. Especially if you use AL80 cylinders.

So if you say use it a bit on the first dive you are most likely out of luck for the second dive unless you go to the shop again

 

[spectrum]

I don't understand. How could they have worse characteristics? A certain amount of air has the same weight whether it is in an aluminum or steel tank. Are you referring to them being more negative? Why is that worse? At most they could only be a pound or two more dry weight. I can't see that being an issue.

Using steel for back gas is a no brainer in most cases for all of the weight/buoyancy advantages.

The loading of a pony is asymmetrical so the closer to neutral the better. Also since in many configurations it's subject being handed-off you don't want it to represent much of your ballast.

Pete

 

[hypertech]

I use HP steel main tanks. I don't see using a little air as an issue. I don't do overhead diving, so I only need enough to solve a problem (maybe entanglement or something), and get up to the surface. 13cf is enough and the extra is margin for extra air usage caused by stress.

Is one pound really that big a deal? The AL30 is -1 full and the steel referenced above is -2.

The 30 just seems like it would be big. I used one once and it felt big. Perhaps I just wasn't used to it. I was thinking of getting a 19, but that steel gets me a little more air in a small tank.