Even Older Twin 38s

[SurfLung]

- At the Wazee Vintage Dive last weekend, my buddy Sea Hunt Jerry says, "Hey, the dive shop has some old twin 38s... You should buy 'em". Well, I need these like a hole in the head but dang if they aren't the real roundy bottom ones like early Mike Nelson... Only they're even older than that because of the bushings. The salesman says $100. I said "Would you take $50?". He's says "Cash?". I say "Ok" and suddenly they're mine.

- So then he hands me a single hose Scuba Pro reg with a nice Dacor SPG attached. "It goes with the tanks". Cripes... Heck of a deal, I think. I have an identical Dacor SPG that works great.
- The tanks are identical but the markings are not. The 3A USN tank was born in'42. The 3AA tank markings are harder to read... looks like '52. The valves are Frankenstein... One side is Voit and one side is USD with a USD center. Bands look like 1960's era with nylon (not cotton) webbing... When did these tanks become a set? Matching hydros start in '68 and continue into '73, '76, and '82.
- The silver/gray finish seems like a heck of a durable finish. Even the scratches on the bottom aren't rusty. Got some rust under the tank bands but not much.
- I can't fit these in my vise to take off the valves and look inside. So, I'll take a short cut and just bring them up to my Brainerd hydro guy... I'll let him take off the valves and bushings and give them a hydro and inspection. If they pass, I'll reassemble with the new high pressure stainless bushings.
- The external gray finish seems pretty long lasting... I don't think I should strip it off to re-paint. Any comments out there in Sea Hunt land?

[captain]

The upper tank band is on upside down

[swimjim]

Nice score Eben!

Jim

[antique diver]

- .....- The external gray finish seems pretty long lasting... I don't think I should strip it off to re-paint. Any comments out there in Sea Hunt land?

I think I would just leave the finish as it is... they look experienced.
Actually, they look galvanized in the photo.

[Herman]

What SP reg?? A nice MK-5/109 is worth what you paid + on ebay. You may have actually made money in the deal.

[SurfLung]

- I don't know my ScubaPro regs at all... So here is what I got with the tanks. I'd appreciate if someone could tell me which SP reg this is.

[luis]

That is a Scubapro Mk-5 from the 1970's. IMO, it is one of the all-time classic single hose regulators.

The second stage included with the Mk-5 is the well known 109. That second stage has a huge following. It is probably one of the most desirable second stages even to this day.

It was first introduced around 1967 and it is still supported today. Actually most of the internal parts are shared by some of the newest Scubapro second stages.

[antique diver]

That is a Scubapro Mk-5 from the 1970's. IMO, it is one of the all-time classic single hose regulators.

The second stage included with the Mk-5 is the well known 109. That second stage has a huge following. It is probably one of the most desirable second stages even to this day.

It was first introduced around 1967 and it is still supported today. Actually most of the internal parts are shared by some of the newest Scubapro second stages.

In other words: "It's a Keeper"!

[1969ivan1]

Eben, you got a steal1

[SurfLung]

Son of a gun... Thanks for identifying the regulator for me. Icing on the cake! With regard to the tanks, I believe I saw some crazy nut pay over $300 for a similar set in similar condition last year. If the tanks pass hydrotest and inspection they will be a fun and satisfying project to restore.

[SurfLung]

Here's My Thinking on Bushings...
- I have a bushing neck Vigo 18 that was assembled by USD and had never been disassembled for hydro/inspection. That one, I had to figure USD knew what they were doing and installed the correct high pressure bushing.
- On THESE tanks, the paint, dates, valve/yoke mismatch, '60s harness, etc... All suggests these were surplus tanks that the owner converted to Scuba. In which case, he may or may not have installed the correct high pressure bushings.
- So, if they pass hydro/inspection, I think I'll replace the bushings with the new stainless high pressure ones.
Question for Geoff - I saw your new bushings on your thread at viewtopic.php?f=41&t=6175. And I have the McMasters link from the Captain. Would you mind telling me the part number you ordered?

- Above is a photo from Geoff's posting/thread and identical tanks.

[gj1963]

Sorry I did not get to look up the number until now. Found the original invoice.
Part I used is:

http://www.mcmaster.com/#50925k362/=ov0pdc

Now there was a lot of back and forth about zinc plated steel vs. Stainless in my original thread. I opted for the zinc plated steel as I have seen stainless gall pretty catastrophically in other applications. I soaked the lower portion in vinegar until the zinc mostly came off then wire brushed it until it had a good polish. May not have been the ideal solution, but the tanks have been in regular service for over a year now.

[SurfLung]

- Thanks Geoff, That's a big help.
- Exciting Update... I finally took the valves off these tanks and you would not believe the inside. They are clean, shiney steel inside. Judging from the outside, I expected them to be rusty and pitted... But they have ZERO Rust... They look like brand new on the inside. Isn't that amazing?

[SurfLung]

My Scuba Tank Vise

- I saw this idea for a scuba tank vise on another forum when I was looking around the internet for some kind of cylinder vise. Commercial vises are priced into the hundreds. Parts for this one cost $10 and change...
- I used it to unscrew the original steel bushings from these little twin 38 tanks. It worked great! Now to get these little tanks hydro tested. I'm thinking to just clean up (not paint) these tanks after hydro testing...

I think I would just leave the finish as it is... they look experienced.
Actually, they look galvanized in the photo.

- On closer inspection, they look galvanized to me, too. In fact, they look like the galvanizing almost hides some of the original markings. Top yellow is definitely paint. But the silver stuff is tougher than paint and where the bottoms are scuffed, it looks more like galvanized than paint.

[SurfLung]

Passed Hydro and Visual Inspection