Even Older Twin 38s

[antique diver]

On other types of paint I use "Saran Wrap" or equivalent to cover the paint surface down in the can. It can be a larger piece, and it is so flexible that I can smooth it out over the paint surface and up the inside walls of the cans. Works pretty good on keeping the paint from drying, and I suppose that would work with the Galvalite also.

[couv]

Hi Eben,

Great job on those tanks. Until I got your email, I did not know you were on VDH-great to see you here.

Here are a few before & after pix of the 109.

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[SurfLung]

Question on a Leaking Yoke...
- Putting these tanks back together, and I'm having trouble getting the connection between the reserve valve and the center yoke to seal up.
- Before re-assembly I unscrewed the brass cup from the reserve valve because it was quite dirty and I wanted to clean it. I replaced the ?? mystery gasket with a suitable O-Ring (not sure if its the right size to actually seal like the gasket. But considering the hole down the middle, I don't think that gasket actually sealed any air (nor was it intended to) in the first place.
- So, the leakage I'm getting has to simply be in the connection between the ball of the center valve and the brass cup of the reserve valve. Am I right?
(Oh now I'm seeing where air could leak over the threads of the cup and bypass
the ball and cup connection).

Hi Eben,

Great job on those tanks. Until I got your email, I did not know you were on VDH-great to see you here.

Thanks Robert. You sure did a nice job restoring the ScubaPro 109 regulator!

[antique diver]

That gasket is definitely needed to seal the nipple socket [cup] into the valve body or air will leak out at the nut and nipple [ball] connection. A copper washer should work well if you can't find a nylon or similar version of the original. Let me know if you don't come up with something and I can check at my building this weekend.

If you replace it and still have a leak then you could suspect a poor sealing surface on the nipple or socket... but there are flared copper washers that can take care of that too.

[SurfLung]

An Embarrassing Solution...
- Took it all apart, checked the O-Ring I used to replace the ?? gasket... Seemed to be the right size. Lightly greased it so it wouldn't bunch when tightened against. Teflon taped the threads of the brass cup just for good measure (Teflon Tape seals the non-tapered threads of our muzzleloader breech plugs against the pressure of firing).
- Cleaned and lightly greased the ball and socket for a good seat.
- This time I pressurized up to 700 psi and listened... DANG! Still leaking. Listened closer and it was the same reserve side of the yoke. Tightened the big nut but it didn't change anything... Listened closer... Still thinking it was either the ball socket or the ?? gasket... Have I got anybody in suspense yet? Well, finally I found it...
- It was the old burst disk! The darned thing wasn't completely tight. I just snugged it up enough to stop the leak and... Problem Solved! Duh! (I've got new burst disks coming from Bryan to replace these old ones.)
- OK... Leak solved, I filled the assembled tanks and yoke up to 1800 psi and left them overnight... This morning I checked and they held pressure and still no leaks.
- Now I just have to finish up the harness and band installation... Hope to have a pretty picture for you sometime next week.

[captain]

No copper washer or O ring was originally used on the CGA 510 nipple and nut connection used on the USD manifold. The usual cause of leaks is a scored surface on the ball end of the nipple. I spin them in my lathe and used 400 grit sandpaper to polish out any roughness in the nipples. When assembling them lay the tanks on a flat surface, align the center section with the nuts hand tight, sit on the cylinders and using two wrenches tighten both nuts at the same time to to avoid the center section turning in the end section which is what causing the scoring. This is one of the few times where you really have to use gorilla strength on the nuts when tightening them to mash the brass together to get a seal if the sealing surfaces aren't perfect.

[luis]

Another thing that helps the sealing is to make sure that the nipple and receiving cup are very clean.

This is a metal to metal sealing design. Any kind of dirt, grease, silicone spray, or any kind of lubricant can be counterproductive when making the metal to metal seal. The connection has to be tightened even harder to displace any grease or lubricant.


I think Surflung is referring to the threaded insert (that doubles as the receiving cup) inside the reserve end of the valve. If I recall correctly that did use a copper washer, but I am not sure. After that part is installed then there is the typical nipple seal. It has been a long time since I worked on one of those manifold, so I don't remember the details.

[captain]

The J valve seat and spring retainer used an O ring not a metal washer. I have new replacements if anyone need one.

[SurfLung]

Almost Finished...

- Thanks for all the help and encouragement. These turned out pretty nice if I do say so myself. The bands are the originals that were coated with black vinyl. I used acetone to soften and strip off the old vinyl. Then, sand blasted them to remove all of the corrosion... Which was heavy. The galvalite works well to fill in a lot of the corrosion pits on these bands and looks good with the tanks.
- Interesting Note: These tanks are different from one another. The necks are a different length. It seems to work out because I think the overall lengths are pretty close. Definitely a "Home-Built" set of Mike Nelson wannabe doubles. You will note that one side has a Voit valve and one side has a US Divers valve?
- Original Harnesses... I cleaned them up with hot water, Dove detergent, and a toothbrush. Still got some blue corrosion on the D-Rings. They're pretty stiff but still quite useable.
- What's Left? I'm going to replace the lead plug Burst Disks, and I want to swap in 3/8 zinc plated bolts for the tank bands. I used stainless 1/4 bolts and stainless galls and locks the threads when I tighten them. Stainless even did that when I used 3/8 bolts on my twin 42 bands. But the zinc plated bolts worked great.

[frogman63]

Those tanks look great. In my USD 38 rebuild project last summer, I replaced the rusted band bolts with stainless steel and didn't notice any problems; I am going to have to keep a watch on that. Thanks for sharing.
Brian

[SurfLung]

- Thanks for your compliment... They are kind MUTTs... With mismatched tanks and valves... Tank bands and harness aren't original either. But after working on them all this time, they have kind of grown on me. I wonder about the diver who originally assembled them... He must have been on a budget... Or maybe he wanted his Mike Nelson doubles to have both Voit and USD parts for a reason? I'm hoping they are close to neutral buoyancy when I actually dive them.
- I'm kind of Ham Handed with tightening nuts and bolts. (I wrecked a few burst disks tightening them too much). The stainless nuts and bolts seized up after tightening and then trying to loosen them for re-positioning. Maybe I over-tightened them in the first place BUT, it's happened a couple of times and has NEVER happened with zinc plated carbon steel nuts and bolts.
- Going to try these tanks out tonight at the Sea Hunt Night event put on by Aqua Venture Dive Shop and Sea Hunt Jerry. Should be fun!

[captain]

Stainless on stainless tends to gaul easily if over tightened. The solution is anti-seize compound and do not gorilla tighten them or use brass fasteners.

[sitkadiver]

Your tanks look outstanding. I never would have noticed the Voit and USD mixed manifold if you hadn't pointed it out. Even the tank necks would have gone unnoticed. What a great find. And thank You for sharing.

[SurfLung]

Your tanks look outstanding. I never would have noticed the Voit and USD mixed manifold if you hadn't pointed it out. Even the tank necks would have gone unnoticed. What a great find. And thank You for sharing.

- Thank you. I'm very pleased with them, too... I got to dive them at the Sea Hunt Night event put on by Sea Hunt Jerry and AquaVenture Dive Shop. Very comfortable to dive with. Here are my findings.
- #1 No major leaks... Out of all four taper thread connections and the double tank valve yoke connections, I have ZERO LEAKAGE. But I knew I had a slow leak somewhere as the pressure would slowly go down. Under water we discovered it was the OTHER burst disk nut (remember above I had to tighten one of them that had a faster leak?)
- #2 These tanks either float or are awfully close to neutral. The bottoms want to lift away from my back.
I had to wear 6 lbs of weight to get neutral with no wetsuit. I like this.
- #3 The original nylon harness is pretty stiff and almost too small for me... The chest strap rides kind of high. One of the other divers said I should try soaking it in fabric softener.

Here are some pictures from the Sea Hunt Night event...

[simonbeans]

#3 The original nylon harness is pretty stiff and almost too small for me... The chest strap rides kind of high. One of the other divers said I should try soaking it in fabric softener.

Or, http://www.vintagescubastuff.com