Tank ID Question - PST 1800 PSI

[Luis H]

These tanks are PST.

I mentioned Scubapro because you mentioned Scubapro manifold and I thought it might have been an original set, but that may not be the case.

I also have another set of small tanks that are Norris and have 2015 psi stamped on them (they also have a +). This tanks I do believe were distributed by Scubapro as a set of small double.

 

[spectrum]

The MP72's, again, are almost identical to the 1800's in outer dimensions, but when full as a pair they are more than 22 lbs negative, not including the manifold and bands.

That sounds like the white Faber, often branded for ScubaPro. I have one and it's a nice little cylinder.

Pete

 

[mahjong]

Yes, the Faber MP72, 3000 psi, comes in white--chromemoly. Scubapro distributed them before XS Scuba, and now I believe Blue Steel is the US distriutor. I have two white ones doubled up. Prior to the white chromemoly finish, Scubapro distributed them with a galvanized finish, and I have two of these as well.

That sounds like the white Faber, often branded for ScubaPro. I have one and it's a nice little cylinder.

Pete

 

[duckbill]

I have a very similar set of doubles (21” tall x 6.85” OD)

They are stamped for 1800 psi and they have a + therefore their working pressure is 1980 psi. The first hydro was plus stamped and during the last hydro on 6/11 they both received a + stamp again.

I measured the internal volume using a precise scale and measuring the weigh of the water capacity and at 1980 psi they hold 46.5 cu ft and 46 cu ft.

The average wall thickness for the two tanks is 0.147” and 0.134”, measured with ultrasonic test equipment.

The REE numbers for these two tanks are 47.1 cc and 46.3 cc.

In salt water the set is 1.6 Lb negative when full (tanks, bands, and manifold, no regulator); this makes them 5.3 Lb positive when empty.

The combined two tanks hold 92.5 cu ft of air at STP (standard temperature and pressure), since air at STP is about 0.075 Lb/ cu ft, therefore the tanks hold 6.9 Lb of air (when full).

This is excellent information, and close enough to my data to think they are the same cylinders.

As I recall, I used the air equalization method to calculate their capacities, and rounded to 50 CF each. Your measurements are surely more accurate in that regard, so these may well be "45s" at 1980 psi instead of the 50s I thought they were.

My working set distributed by Healthways was manufactured in 1971. What year(s) are your cylinders?

Thankyou for sharing your measurements and calculations.

 

[Luis H]

My 1800 psi cylinders did not start as a match pair. One has an original hydro date of 7/74 and the other is 7/79.

They are very similar, but I can tell that one has seen a lot more use than the other.

The physical dimensions are very similar, but one is almost 1/8” taller than. That is not uncommon for same model tanks, but it is annoying for a set of doubles. I put a small shim inside the boot of the shorter one.


In addition to those PST tanks I also have two sets of Norris 2015 psi and what will become a set of Walter Kiddy 2250 psi. The Norris and the Walter Kiddy are about 18.5” tall.

The diameter of the Norris are just a tad smaller (6.8&#8221 which is enough that the boot will fall off if I don’t put a plastic wedge in them. I always use the draining style tank boots (with the mostly open bottom).

I have only tested one of the Norris sets (this fall I will test the other Norris pair and the Walter Kiddy). The two Norris tanks that I tested are 45.3 cu ft and 45.9 cu ft at 2217 psi.