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SurfLung
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First Name: Eben
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ScubaPro Twin 45s

Mon Mar 15, 2021 4:51 pm

ScubaPro Twin 45s
Image
- My buddy Rich just acquired a set of ScubaPro tanks that are sized like the proverbial "Twin 38s" but unlike our familiar 1800 psi and 1880 psi working pressures, these are marked 2015 psi. We know they are ScubaPro so I did a little research into the ScubaPro catalog collection on VDS.
- In 1970 and 71, they called these "Twin 40s" and gave no pressure data. In 1972, they actually referred to them as "Twin 38s" but still gave no pressure data. Then in 1973, they called them "Twin45s" at 2200 psi. They stuck with that description in '74 and '75. But then in 1976 they finally gave some useful numbers: 45 cf at 2216 psi with a working pressure of 2015 psi.
- Well I did a little calculating with the pressure and volume numbers and came up with the following.

2216 - 45 cf
2015 - 40.9 cf
1880 - 38.1 cf
1800 - 36.5 cf


The other Twin 38s that I know of at 1880 psi are Sportsways. So really all that this calculating tells us is that the size of these tanks is about the same as all "Twin 38s". But the higher pressure will most likely mean thicker steel and heavier weight. I think I'll weigh some Various Twin 38s to see how they differ in weight. :)
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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ScubaLawyer
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Re: ScubaPro Twin 45s

Thu Mar 18, 2021 3:14 pm

My ScubaPro Twin 45s are my go-to daily diver now. Just had them hydro'd. They had the thick vinyl black coating on them that was peeling off so I had them sand-blasted and zinc'd. The original hydro date was 1976. I have had them for about 8 years now. For a size comparison, here they are (on left) next to my Sportsways 38/42's (on right). Very cool find!

Image
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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SurfLung
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Re: ScubaPro Twin 45s

Fri Mar 19, 2021 11:41 am

Clarification...
- The numbers on my last post are all for the ScubaPro tanks but I may have given the impression they were for the other brands. Here's what I believe is the correct pressures and volumes for our more familiar Twin 38s:

US Divers Twin 38s
Tanks marked 1800 psi. are 38 cf. Filled 10% over are 1980 psi and 41.8 cf

USN Surplus 38s
Tanks marked 1800 psi. are 38 cf. Filled 10% over are 1980 psi and 41.8 cf

Sportsways Twin 42s
Tanks Marked 1880 psi are 38 cf. Filled 10% over are 2068 psi and 41.8 cf

ScubaPro Twin 45s
Tanks marked 2015 psi are 40.9 cf. Filled 10% over are 2216.5 psi and 44.99 cf

Voit Twin 50s
Tanks Marked 2250 psi are 45 cf. Filled 10% over are 2475 psi and 50 cf.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

SnarkIII
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Location: Lawrence MA

Re: ScubaPro Twin 45s

Fri Mar 19, 2021 12:35 pm

Eban, thanks for sharing this info. I have a Scubapro tank that wasn't mentioned in your list. It's about 17 1/2 inches high 6.9 diam and rated at 2250. The original Hydro date is April 1970. I thought this was what Scubapro was referring to in the 1970 catalogue as their "high pressure tank"

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captain
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Re: ScubaPro Twin 45s

Sat Mar 20, 2021 10:40 am

Not sure that the Navy surplus 38's were/can be filled 10% over. They were 3A spec. tanks for mostly CO2 life raft inflation or aviation breathing oxygen. Don't recall ever seeing one with a +. Luis may have better info than me.
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swimjim
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Re: ScubaPro Twin 45s

Sat Mar 20, 2021 4:53 pm

captain wrote:
Sat Mar 20, 2021 10:40 am
Not sure that the Navy surplus 38's were/can be filled 10% over. They were 3A spec. tanks for mostly CO2 life raft inflation or aviation breathing oxygen. Don't recall ever seeing one with a +. Luis may have better info than me.
I've got a steel 72 that has a star stamped on it. That's not supposed to be on anything scuba. Just takes the right guy with the punch I guess. Lol

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