1st tank purchase (help!)

[Ari]

I found that tese tanks have the best buoyancy and CG for my needs. They also last for a long time.

Mine is a TorTec 15 liter, 232bar tank. I have just changed the valve (and reg) to DIN for more safety and comfort.

Please excuse the metric units. This is how we work around here.

Ari

 

[Uncle Pug]

I don't think there is going to be a big enough difference to matter...

...course my tanks have consecutive serial numbers

Seriously... don't worry about it.... just don't hook and ox and a mule together with the same yoke.

 

[Tavi]

.................The tanks you choose to double-up should be the same height. Steel cylinders in the same series can vary considerably in height.

There is a lot of info there

 

[pescador775]

I don't see how tanks 'in the same series' can vary in height. The production should be run on the same equipment and carefully controlled. Having said that, I have seen three PST HP 100 tanks, mfgd in different years, and having three variations in shoulder and neck. However, there was nothing that would prevent a doubles set from being made up that I could see. I didn't measure them with a caliper though. A real problem would crop up if one were to attempt to mate a Genesis 100 and PST/USD/AquaAire/Sherwood 100. The Genesis is very different from those.

Speedster should decide now if he is going to a dry suit. In that case, purchasing an LP steel now makes sense. Otherwise, should go with aluminum. The 'super 80', I believe is approx neutral buoyant. If a heavy backplate is used, the standard 80 (77.4 cf) might be best choice. Since he plans to use multiple regs and Lord knows what else, the connections would be cleaned up by going with DIN valves. I suspect he will go dry. UW times including decom are so extended with doubles that chill is a factor.

 

[SLJ]

One time I bought two pst 104's for doubles and they were different heights. I ended up making them singles as they just wouldn't sit right and really bothered me. They do make excellent single tanks or big O2 deco bottles for cave diving where they are dropped right away.
SLJ

 

[O-ring]

Both of my doubles are lopsided...my 72s are different sizes and my AL80s (both Catalina 80s purchased within 4 months of each other) are too. It doesn't seem to make a big difference...the tanks just sit a little to one side on a flat surface on dry land. I could probably aquaseal a couple quarters to the bottom of each tank, but I felt it wasn't worth it since the difference isn't huge and I don't think it is straining the manifold since I have HM bands on the tanks.

Another guy I know has a set of double 120s that are different heights. He corrected it by coiling thin rope in the bottom of a tank boot and then putting boots on both tanks with the rope fitted boot on the shorter tank.

Does it bug me? @#*&!&@ yes it bugs me..my dive buddies give me grief about it all the time...

 

[SPEEDSTER]

so perhaps I should wait on the 104 and get the din 80? Use it for deco/stage later? I had no idea there actually were significant dif. between *same* volume tanks.

-m

 

[large_diver]

If you are only in the market for one tank and are unsure about your future diving, you might want to go with the 80 for now, simply due to the lower cost ($100+ vs. ~$300 for a 104). A $100 "mistake" is easier to undo than a $300 one ;-) Keep in mind however that 104s are always in demand, so they are not hard to get rid of if you change your mind......

That being said -- I dive singles wet and use a 104 (also an OMS 98, which I would not buy again). The biggest advantage (other than volume) is the filling -- my LDS can always give me a full fill+ without having to leave the tank overnight. HPs...they need more time to get a complete fill.

My $0.02.