Need help identifying these tanks.

[Sortsol]

Hey all, I picked these up and just had them hydro'd. they are 22 years old, but look in perfect condition. thinking of using them for sidemount, but can't identify the manufacture or decipher most of the print on the tanks. They don't match what I can find. Anyone have any ideas?

 

[swimlikethefish]

Looks simple.

PST 100

Has an E9791 exemption and a fill pressure of 3500. Galvanized coating. Probably 7/8 thread, din only. Could be a 120 but without a picture of the full size it would be hard to tell.

 

[CT-Rich]

Both are stamped 91 they both have a lone 81 on it. They are at least 28 years old, possibly 38 years old.

 

[tbone1004]

Both are stamped 91 they both have a lone 81 on it. They are at least 28 years old, possibly 38 years old.

where did you see the 91? The original hydro stamp in picture 4 is 12-97. Those tanks weren't made in the early 80's or 90's.

@swimlikethefish was correct, they are PST high pressure tanks. Which specific one is unknown from the pictures, could be 80's, 100's, or 120's. They will have 7/8 valves, and they will be 300bar DIN only. They are also hot dipped galvanized which is ideal for the salty stuff.
They are very high quality tanks and it looks like they have been well taken care of.

If you go here
SCUBA Cylinder Specifications – Huron Scuba, Snorkel & Adventure Travel Inc. PADI 5 star IDC in Ann Arbor, MI
and look down the list for the PST tanks that have a working pressure of 3500psi, you'll see the tank specs for those bottles. Get the rough height without the valve and that will tell you if it's a 80/100/120

 

[Sortsol]

Wow, 38 years... you'd not know it from how they look and they've only had three hydro's. I was told they are HP120's. They have 300 Bar DIN only valves on them.

Wrote the above before I saw tbone1004's response. Great info all, thanks!

 

[swimlikethefish]

PST

^ that is the manufacturer

 

[eeel]

Wow, 38 years... you'd not know it from how they look and they've only had three hydro's. I was told they are HP120's. They have 300 Bar DINonly valves on them. Any way to tell manufacturer?

Pressed Steel

pressed steel tank company - Google Search

 

[James79]

where did you see the 91? The original hydro stamp in picture 4 is 12-97.

I believe @CT-Rich saw the 97 as a 91.... I did the same at first glance, the blue paint on the new hydro covers the upper bar of the 7.
Respectfully,
James

 

[greeniguana]

They are USD HP35 tanks made by PST. 7/8 valves.

The two I have were made in 1998 and were also hydro'd in 8/12 and painted with red paint......

 

[Zef]

DOT = US Department of Transportation
E9791 = Pressed steel tank
3500 = working/service pressure in PSI
TP5250 = test pressure in PSI
IA 81 = I believe this is a manufacturers mark (company = Pressed Steel tank company)
63176/618198 = I believe these are the manufacturer's serial numbers for the respective cylinders
The next mark after the the serial numbers is either the manufacturer's touch mark or the independent inspection facility's touch mark.
4-98 = April 1997 hydrostatic test date (could be the original test date of the respective cylinder)
12-97 = December 1997 hydrostatic test date (could be the original test date of the respective cylinder)
8-12 = August 2012 hydrostatic test date (I believe the marks between the numbers indicate the facility that did the test)
7-20 - July 2020 hydrostatic test date (I believe the marks between the numbers indicate the facility that did the test)

-Z