ASSAI (Sherwood/Genesis) Old vs New tanks

[JohnN]

I have a set of "older" Assai HP120 tanks (3500 PSI - 7/8" necks). They have had two hydro's (last was in 2012) so they are at least 12 years old.

Current Assai tanks are 3442 - 3/4" necks. I can find specs for the "new" variant, does anyone have buoyancy specs (full & 500 PSI) for the old ones.

 

[tbone1004]

they're Asahi. The old ones should be similar to the PST tank specs, when they went to the 3442 tanks the alloys were changed with a few other dimension changes, so the buoyancy and heights are a bit different. You can calculate the 500psi buoyancy yourself, 120*.08/7 will give you the weight of the air so just add that to whatever the empty buoyancy is. That being said, the 500psi buoyancy is not relevant because you have to plan for worst case scenario and that means you'll be likely breathing heavier when your tank is that low due to stress so you never want to plan weight based off of partially full buoyancy numbers....

 

[kwinter]

Not sure I agree with tbone. The old Asahi 3500s and the old PST 3500s were very different tanks. Different sizes, different buoyancy characteristics, different looks. I had one Asahi that I sold because it wasn't close to the PSTs. I thought the new Asahi tanks were identical to the old ones, but XS Scuba (I think) pushed them to mark them 3442 so they could use 200 bar convertible valves for yoke regs.

I could be wrong about the latter part, but I am certain about the first part.

 

[tbone1004]

then I stand corrected, thought they were almost identical to the older PST's

 

[Leadking]

Asahi tanks are spun tanks. The only reason they are now 3442psi is to be able to use a yoke valve. Do a search on Scubaboard about my comments about John Dimek at PST for more info

 

[JohnN]

Asahi tanks are spun tanks. The only reason they are now 3442psi is to be able to use a yoke valve. Do a search on Scubaboard about my comments about John Dimek at PST for more info

Do you have a link? google "site:www.scubaboard.com John Dimek" is coming up empty as is the ever useful built-in scubaboard search. . .

 

[Leadking]

From a post of August 10, 2011 http://www.scubaboard.com/forums/tanks-valves-bands/391357-hp-vs-lp-5.html
From a post over five years ago;
U.S.tensile strength for 3AA cylinders (105,000-125,000 psi) is not the same as European tensile strength (135,000-155,000 psi as required by EN 1964 part 1 and ISO 9809 part 1) and I have test data that shows Faber cylinders delivered to us show a tensile strength of 115,000-123,000 psi (as required by DOT)

The genius behind the design of Exempt tanks was John Dimik (spelling may not be correct) of the old Pressed Steel Tank. He used the same tooling with a new high strength steel that was developed. Everyone assumes because the sizes are the same, everything is the same, FALSE. Exempt cylinders are made from a completely different steel than 3AA cylinders. I will keep posting accurate, honest information each time I find these posts which I consider mis-leading at a minimum and dangerous at most