Identifying old Pst tanks

[olphart]

I have 2 PST steel tanks that are 7" dia and 24" high (w/o valve)
DOT 3aaa 3000
2628t
Pst
11 76+
I was told that they are 96 cu ft.
Is that correct?

 

[halocline]

I don't know, sounds a little small for 96cft, but I bet they'd make great doubles. Are they really heavy?

 

[olphart]

Oh yeah! very heavy

 

[olphart]

Hmm, it looks like no one knows the size. Bummer!

 

[Couv]

OK I was hoping someone with better math skills than me (Awap) will give you a simpler method; but the rascals have abandoned us; so here's one way. Transfer a known volume into the PST tank. Divide that volume by the pressure now in the tank to give you a constant. Next, multiply the constant by the working pressure to give you the volume at working pressure.

For instance, let's say you rent/borrow/buy/steal an AL 80 which actually holds 77 cu ft. at 3000psi

77 divided by 3000 gives you the constant (0.0256 cu ft per psi) for the 80

Transfer a known amount out of the 80 and into the PST (let's say take it down to 2000)
1000 x 0.0256 = 25.6 cu ft out of the 80 and into the PST

So now, we measure the psi in the PST tank and we have say 900 lbs
25.6/900 = 0.0284 our constant for the PST tank.
0.0284 X the working pressure 3000 give us the full volume 85.2 cu ft.


couv

 

[Mitchell Teeters]

OK I was hoping someone with better math skills than me (Awap) will give you a simpler method; but the rascals have abandoned us; so here's one way. Transfer a known volume into the PST tank. Divide that volume by the pressure now in the tank to give you a constant. Next, multiply the constant by the working pressure to give you the volume at working pressure.

For instance, let's say you rent/borrow/buy/steal an AL 80 which actually holds 77 cu ft. at 3000psi

77 divided by 3000 gives you the constant (0.0256 cu ft per psi) for the 80

Transfer a known amount out of the 80 and into the PST (let's say take it down to 2000)
1000 x 0.0256 = 25.6 cu ft out of the 80 and into the PST

So now, we measure the psi in the PST tank and we have say 900 lbs
25.6/900 = 0.0284 our constant for the PST tank.
0.0284 X the working pressure 3000 give us the full volume 85.2 cu ft.


couv

Damn I don't have enough fingers and toes to figure that one out. :dork:

 

[oxyhacker]

PST made some oddball 3000 steel 3AAAs some years back which were about the size of a 72 but thicker walled and, as a result much heavier. They were claimed to hold 80 cf, but whether that was with the "+" or not I cannot recall offhand. But that would sound like what you have. Perfectly respectable tanks - I wouldn't mind having a few. Being made to the bulletproof old 3AA specification they were probably notably heavier than a modern exemption tank of similar size and capacity would be - I'd be interested to know what they weigh.

Divers in those pre-BC days used to strap them on thinking they were 72s and sink straight to the bottom. Or at least that is the legend.

 

[mahjong]

If those are 72's I can see why divers would sink--that's a lot of tank for 72 cuft of air. Faber MP72's (3000psi +) are just under 21" tall and 6.84" in diameter. According to the 1987 Scubapro catalog these tanks are -11 lbs full, though current spec charts have them at ~ -8.5 lbs.

PST made some oddball 3000 steel 3AAAs some years back which were about the size of a 72 but thicker walled and, as a result much heavier. They were claimed to hold 80 cf, but whether that was with the "+" or not I cannot recall offhand. But that would sound like what you have. Perfectly respectable tanks - I wouldn't mind having a few. Being made to the bulletproof old 3AA specification they were probably notably heavier than a modern exemption tank of similar size and capacity would be - I'd be interested to know what they weigh.

Divers in those pre-BC days used to strap them on thinking they were 72s and sink straight to the bottom. Or at least that is the legend.