Which brand of steel cylinder / tank should I buy?

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Pity we all picked an expesive hobby. i can remember when i finished OW and i could get all my basic scuba gear for $1000. Now of course just a nice set of doubles run a grand.

TMD
 
Last two sets of lp95 doubles were $400 and $300 #1 had Dive-rite manifold &bands #2 had OMS (yuk) I waited around the shop looking for deals on tanks(it seems the first cave dive thins out the crowd a lot)New tanks are athing of the past for me.Remember to include hydros and cleanings in the price too.Ginnie has a yearly sale and so do a lot of the local shops to get rid of excess toys.Waiting on a good price on a good tri-lam suit now.
 
Originally posted by VTWarrenG
Is there a big table somewhere that will help me make sense of all this madness??
There is probably more "official" misinformation floating around out on the net about tanks and their properties than about just about anything.
When you look at published numbers, it's nice to have a little physics tucked away in your back pocket, so you can recognize "reasonable" in a table immediately, and BS as well. For example, at everyday temperatures and average sea level pressure, air weighs about .08 pounds per cubic foot, or about 1.3 grams/l. With that in mind, you can immediately calculate that the difference in actual weight of an empty and full 100 CF tank is 8 pounds (or the difference in the weight of an empty 10 l tank and one filled with 200 atmospheres is 2.6 kilos). When you're talking buoyancy, this difference in physical weight can be offset just a tad by expansion (and therefore increased displacement) of the tank, but if you see numbers that are very much off that simple calculation based on the weight of the air being put in the cylinder the numbers are suspect.
Another factor that comes into play is the displacement of the lead used as counter weight to buoyancy. Since water is about 1/13 as dense as lead, there's actually a 1.08 ratio when comparing the actual weight change of a constant displacement body to the lead required to counter the change in buoyancy. That is, if you use twelve pounds of air out of a set of doubles during a dive, you'll need to carry 13 pounds of lead to balance it.
Have fun with the tables...
Rick
 
The specific gravity of lead is 11.3 which means water is about 1/11 as heavy as lead.
 
Originally posted by Rick Murchison
When you're talking buoyancy, this difference in physical weight can be offset just a tad by expansion (and therefore increased displacement) of the tank...
You can safely ignore expansion completely. Have you ever seen the size of the burette used during a hydro test? And those cylinders are going to 5/3rds (3/2ves for PST HPs) of their working pressure!

Working pressure expansion of a cylinder is essentially zero. It probably IS zero for an AL.

Roak
 
Originally posted by devjr
The specific gravity of lead is 11.3 which means water is about 1/11 as heavy as lead.
Aw, hell, yew caught me! I wuz thinkin' mercury!
11.3 it is! Ratio is 1.09 vice 1.08... sorry. (it still works out to 13 pounds of lead to account fro 12 pounds of air, though, so I don't feel *too* bad)
Rick :)
 
The amount of information on this discussion board is AMAZING. SO MANY knowledgeable people here. Its a pleasure reading this boad.
 
I am in the process of getting steel tanks. HP, LP, size ...all things I am struggling with. I now see something about "pressed steel".

What is "pressed steel" and is this "good"...desirable or less desirable or...what?

Any and all help would be much appreciated!!

Thank you,
Jon
 
Pressed Steel Tanks is the name of the manufacturer.

You can check out their website here. PST Scuba

After all the research I've done, I think you can't go wrong with PST.

I just bought 2 PST LP 104's :thumb:
 
https://www.shearwater.com/products/teric/

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