USDTwin manifold overhaul questions

[ScubaLawyer]

Hello all,

I know nothing about valves and manifolds (there, I said it!). I figure it can't be all rocket science. Anyway, I have a USD Twin manifold that came on a set of Twin Aluminum 50s I bought new in 1976. Two basic questions.

1. What is the best way to clean off the slight corrosion from the surface? Tools, cleaners?

2. Where do I find an overhaul parts kit, or do I just look for generic O-rings, burst discs, etc..

Thanks,

Mark

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[antique diver]

Well, I am going to take a beating for this , but I have had excellent luck with the metal parts in half very warm water and half CLR household cleaner in my Ultrasonic cleaner. It's available at most grocery stores. I run it until the parts look good (usually less than 15 minutes), then wash thoroughly in Simple Green and hot water mix, then just hot water.

I know that many advise against CLR, but it is readily available and works. As for damage to the metal plating: NONE... I tested chromed brass regulator port plugs in this solution for 48 hours just to be sure no damage would be done before I put other important stuff in, and was surprised at the total lack of damage, especially after hearing how bad this was for brass. I have also used White Vinegar along with Simple Green with decent results. Many times in the past I used 1 part pool acid (Hydrochloric) to 4 parts water with good results.

Warning: Don't leave the parts unattended in any of these mixtures for long periods. A few minutes should do the job. Keep your mixtures fresh, as brass salts will build up in the acidic solutions, and can begin to brass/copper plate over your chrome with lengthy soaks! The chrome can end up sort of copper colored.

I have never tried the highly recommended Salt-X, but apparently it is safer.

VDH can probably provide the parts you need. I think all the orings seem standard sizes. If unable to find new valve seats and shaft Teflon seals, I have them... but only provide them if not available from VDH, so please check there first.

[ScubaLawyer]

Antique,

Thanks for the info. I'll take your advice and post my progress.

Mark

[Robohips77]

Cleaning wise ultrasonic cleaner with half warm water and white vinegar 10-1 water to vinegars. I have also used Clear simple green on a 10 -1 basis also. Bryan has all the parts you need in the store and if he doesn't have them he can get them cause he has had all I needed!. A dealer may have some parts in stock but in all reality the store should handle your needs. Good luck and enjoy the repairs!

[ScubaLawyer]

Help please,

Almost done with my USD twin valve/manifold overhaul. I'm only missing one part. It's a black teflon-looking ring. It goes into the opposite end of the J-valve piece. The one I have is not useable. Here are pics of it. If any one has an extra I'd be happy to buy it off you. I asked Bryan and he didn't have one. He suggested I post here. Looking forward to hearing from someone, anyone, please.

Thanks,

Mark

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[antique diver]

Mark, that one is a common trouble-maker. I think I may still have some. Can you get me a good inside diameter measurement so I can be sure. Mine are not filed by part number.

BTW, that valve looks to have cleaned up well.

[ScubaLawyer]

Mark, that one is a common trouble-maker. I think I may still have some. Can you get me a good inside diameter measurement so I can be sure. Mine are not filed by part number.

BTW, that valve looks to have cleaned up well.

Yes, the valve did clean up well. I followed your directions and it worked! Never a doubt in my mind. I'll post a final pic when I get it put back together. Thank you for that advice.

As for the teflon(?) part, here are some more photos. It has a flange type arrangement so there are really two inside measurements. Hope these photos help. The nearest I can tell its as follows:

Inside diameter of outer flange. 19/32 inches. (15 mm)
Inside diameter of inner ring. 15/32 inches (11.5 mm)

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[antique diver]

The seal actually started out flat and extruded up over the outer edge of the socket when it was tightened in.

Thanks for the photo, and I'll look through my valve parts tonight.

[captain]

It's an O ring, it's not flat and not teflon. I think a size -010

[antique diver]

I have the flat washers that you are looking for, and my parts bin was still marked with the correct part number also shown in the Aqualung Repair Manual available online at this website. The same that is on my bookshelf. The number is 0518-06, description is Washer.

I have two versions that I just tried for fit in the same valve as you have, and either one will fit. One is the original OEM flat rubber material like your existing one, and the other is Nylon, and I don't remember if they provided this as a later version or if I got it elsewhere. I would start with the original, as I never had trouble with them.

It is certainly possible that an o-ring of the correct diameter would seal, but for a trouble free seal over the long run you should use the right item. The o-ring might continue to crush down in use and not let the brass socket and ball stay tight enough together to keep an effective metal to metal seal. Anyway, since the correct washers are available you might as well use what the manufacturer did.

If you want me to send them PM me with your mailing address, and I will slip one of each in a simple envelope and mail them. If you like them and they will do the job you can send me $3 and keep the spare one for future use. Wait until you are satisfied that they work. If you decide not to use them just mail them back... no problem.

To install without damaging it, I strongly suggest that you place the washer fully into place down in the valve body, then screw in the ball socket. It will be a snug fit down in the hole (but loose on the socket), and if you install it on the socket first you risk damaging the washer when you snug it down. Tighten the socket very snug with an exact fitting allen wrench.

[captain]

I have used o rings for years in them with never a problem simply because I never had an original part or could I even tell what the original looked like or the material which always appeared to be dried up rubber.

[antique diver]

I have used o rings for years in them with never a problem simply because I never had an original part or could I even tell what the original looked like or the material which always appeared to be dried up rubber.

Captain, you were way ahead of most people that never even realized that the socket unscrewed, much less had a washer under it. Squashed dried up rubber is exactly what you see in most removals, and it's not always recognizable for what it is. We did a large volume of service and repairs, so after learning the hard way, kept them in stock for the occasional doubles set that came through.

[ScubaLawyer]

I have the flat washers that you are looking for, and my parts bin was still marked with the correct part number also shown in the Aqualung Repair Manual available online at this website. The same that is on my bookshelf. The number is 0518-06, description is Washer.

I have two versions that I just tried for fit in the same valve as you have, and either one will fit. One is the original OEM flat rubber material like your existing one, and the other is Nylon, and I don't remember if they provided this as a later version or if I got it elsewhere. I would start with the original, as I never had trouble with them.

It is certainly possible that an o-ring of the correct diameter would seal, but for a trouble free seal over the long run you should use the right item. The o-ring might continue to crush down in use and not let the brass socket and ball stay tight enough together to keep an effective metal to metal seal. Anyway, since the correct washers are available you might as well use what the manufacturer did.

If you want me to send them PM me with your mailing address, and I will slip one of each in a simple envelope and mail them. If you like them and they will do the job you can send me $3 and keep the spare one for future use. Wait until you are satisfied that they work. If you decide not to use them just mail them back... no problem.

To install without damaging it, I strongly suggest that you place the washer fully into place down in the valve body, then screw in the ball socket. It will be a snug fit down in the hole (but loose on the socket), and if you install it on the socket first you risk damaging the washer when you snug it down. Tighten the socket very snug with an exact fitting allen wrench.

PM Sent. Thank you.

Mark

[ScubaLawyer]

UPDATE. The overhaul seems to have worked! Yea! I did get the J-valve mechanism in ass-backwards but that is easily remedied (open is currently up and closed is down position).

No valve or manifold leaks at all. Yea! I do have a leak at the tank neck/valve interface. Can’t figure it out. Always a possibility of it being too tight or loose, defect in o-ring, particulate matter in seal, etc... Before I explore those things, I want to make sure I’m using the right o-ring to begin with. My research shows it’s a 1" size 214. Seems to be the same as the old one I took off. It fit snug over the threads and there is no play in the seated o-ring. Do I hear concurrence or dissent?

Thanks for everyone’s help on this project. I really appreciate it. Mark.

[ScubaLawyer]

SUCCESS!! Sort of ..... Need advice!

My USD twin manifold rebuild project is done! Moreover, the darn thing actually works. It holds air, no valve leaks, the J-valve works, all is great — EXCEPT,

One of my tanks is leaking at the tank neck/valve interface. I replaced the o-ring. Still leaked. I over, under and just right torqued the valve into place. I went from no silicone lube to a tiny bit of lube on the o-ring. Each time it leaked. I switched the valves around and the same tanked still leaked. The other tank was fine. After exhausting all of the possible valve/o-ring/tightness issues, I took a closer look at the tank neck. I just got it back from a Hydro and Visual Eddy Test.

It appears there is now a defect/divot in the metal of the tank neck that is preventing the o-ring from sealing. I tried to take a couple of photos of the defect (posted below in the next reply since apparently 3 pics is the max) to see if anyone has a solution short of scrapping the tank and buying a new one.

Ah, the fun of fixing old stuff! Mark.

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