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Starting down the DH rabbit hole

Discussion in 'Vintage Equipment Diving' started by James79, Nov 1, 2019.

  1. Scuba Lawyer

    Scuba Lawyer Barracuda

    # of Dives: 5,000 - ∞
    Location: Laguna Beach, California
    446
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    Hey John, I'm sure there are many such seals that are just fine. I always remove the body from the can on a rebuild so I can put all parts in the ultrasonic cleaner (or rechrome the cans if necessary). It's only when I get the body and can apart when I can see the actual condition of the seal. At that point it just makes sense to me to put in a new seal since they aren't really resusable anyway once the can/body is separated (IMHO). Anyway, my 2psi. I respect our different approaches. Mark
     
    Sam Miller III likes this.
  2. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    2,870
    1,022
    113
    John, I don't understand this.
    If you don't remove the ring, how do you inspect the seal? How do you determine that it is still flexible and has no cracks?


    Rubber does deteriorate with time. If it is properly stored the useful live of the gasket can be extended, but it is best to inspect it.

    Mil-spec seals are required to have a date of manufacture on the package to account for the effects of aging on the rubber.

    To clean surface corrosion, don't you soak the regulator in vinegar solution? It is a good idea to remove all the seals before soaking in vinegar, but I have heard of some divers that don't.
     
    Scuba Lawyer and Sam Miller III like this.
  3. Perryed

    Perryed Barracuda

    # of Dives: 500 - 999
    Location: Missouri
    217
    157
    43
    The seal has multiple fine line cracks, so I`m pretty sure that's the problem. Got the rebuild kit coming from VDH and that should solve the problem plus any future difficulties. If not, I`ll be back! Love the information available on this forum! Thanks guys!
     
    rhwestfall likes this.
  4. herman

    herman Divemaster

    # of Dives: 500 - 999
    Location: Raleigh,North Carolina
    9,526
    2,107
    113
    Those can seals almost always need replacing. I have rebuilt a number of DA's and RAM's and almost all were hard and crunchy plus you need to remove the cans to do a proper cleaning. By the way, they go BETWEEN the can and body, I have seen a number of them between the can and ring, it will leak if you put it there.. Without the proper tools these regs can be a bear to get apart, mainly because there is no good way to hold them without the tools.
    As for holding pressure, it SHOULD, if it leaks down then there is a small leak somewhere. The 3 most common ones I have seen are the yoke to valve interface, it may have some small scratches or missing chrome, the nozzle is too loose or the hookah port is leaking. The nozzle is usually too loose due to not having the correct tools to hold it while tightening it but there is a second possible issue. If you use the old style pheonic seals, then they require a good bit of torque to get a good seal, conversely if you use the nylon ones Bryan includes in his kit, they require a lot less torque and if you torque them like the old type you can extrude them to the point they leak. The hookah port is often the problem, cleaning it and tightening it will usually fix it.
    On all regs I rebuild, I assemble the body, connect it to a pony tank or a special HP hose I have then dunk it in a bucket of water to look for leaks. It's about a 50/50 shot that something will leak. Not bad, just a few bubbles and ok to dive but it won't hold pressure for long.
    The single stage diaphragms will NOT work without a HPR. You must have the tabs for it to work on the original second stage. I suggest you consider changing them out. The old diaphragm ( unless it has been upgraded to a silicone one) will be stiff and hurt the performance of the reg, even new they were no where near as flexible as the silicone ones are. Another reason is the original second stage is a pain to set up properly. I can do it but I have a lot of experience at it, the HPR is much more plug and play and is very easy to set up.
    If your reg has an old duckbill in it , odds are pretty good it is hard as a rock or a glob of goo.....or both. The best way to remove it is to soak it in denatured alcohol over night. The goo melts away and to the hard stuff turns to a soft jelly that is pretty easy to scrub out with an old tooth brush.

    If you want tools for the DA or RAM and their Voit counterparts, I make a complete line of tools designed specifically for these regs. They will make your life a lot easier when servicing these regs . PM me if you would like a catalog.
     
    rhwestfall, Scuba Lawyer and couv like this.
  5. Perryed

    Perryed Barracuda

    # of Dives: 500 - 999
    Location: Missouri
    217
    157
    43
    I have disassembled and cleaned the reg and replaced the duckbill. It`s in remarkable shape for a DH reg. I` have had it in the pool and it breathes very good. The original hoses are in near perfect condition. Diaphragm is still very flexible. I`ve replaced the hookah port with a 2 into one 3/8th splitter so I can run a BC inflator hose and an octopus (gonna use a rebuilt Scubapro 109). Have a banjo fitting so I can run a vintage pressure gauge. I appreciate the info and will definitely be in touch if I run into trouble. Thanks so much and I`ll let you know how it goes. Just need to get everything installed and get it to the pool again.
     
  6. John C. Ratliff

    John C. Ratliff Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Beaverton, Oregon
    2,721
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    Luis,

    I just looked at the RAM that I got from my brother (he's a retired fisheries biologist who used it for his work). It has one area on this seal that looks like a crack, but is not. It is only the outside area that has cracked. Here's the thing; the rubber that's under the box and body has never seen any chemical, as it is protected by the metal parts. The outside, which is exposed to air, and any chemical that is used to clean the regulator, can deteriorate. But that which is making the seal has not been so exposed. This seal is air-tight, as proven by negative breathing tests (which I just conducted).

    Now, if that ring is removed, the seal will then need replacement, as the seal itself will be damaged by the removal process. But if left alone, it remains air-tight. It's in my opinion (apparently mine only) a case of "if it ain't broke, don't fix it." In other words, the "fixing process" breaks it.

    My LDS does, somewhere, have the two tools to remove this ring. But they have kinda lost them, and I won't remove that ring unless it fails the negative breathing test. In that case, I'll probably talk with Herman and get my own tools.

    SeaRat
     
  7. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    2,870
    1,022
    113
    John,

    Interesting theory and that is exactly what I suspected.

    I am afraid that you are probably going to stand alone on that one, but to help you with your assumptions; the good thing is that there is minimal differential pressure across that seal. Even when you are doing a suction test, you are only applying minimal differential pressure. So if there are any air leaks, they would be miniscule or non-detectable.

    A water leak would probably be also very small and inconsequential.

    One interesting kind of academic issue is that you can actually get a water leak, due to the surface tension of water, even if you can’t detect an air leak. This is a common phenomenon on skylights and some window seals (that water will leak were an air test does not). The good thing is that the magnitude of the leaks is miniscule and any diver probably thinks it is just condensation.

    Now, about your theory that the removal process is what breaks the gasket… you know that is incorrect. If the rubber gasket was not brittle it would not break apart by just unclamping it. Yes, the clamping action is holding the gasket together and if it is not disturbed, you are finding it good enough for you.

    Your theory that only the outside exposed rubber is the only deteriorated part, you also know that is totally incorrect. If the elastomer (rubber) was still elastic, you can take it apart without breaking it. I have done it plenty of times with gaskets that have not deteriorated due to age.


    I should add that I am a strong supporter of the concept that "if it ain't broke, don't fix it", but that is not exactly what we have here. I can see where someone might think so, but not really.
     
    John C. Ratliff likes this.
  8. James79

    James79 Regular of the Pub

    # of Dives: 25 - 49
    Location: Lower Alabama
    261
    203
    43
    On the one I should be receiving tomorrow, I have a potential parts question (getting my explanations ready for the keeper of the budget).
    If I order the HPR and a new diaphragm from VDH, that covers all second stage components.
    If I order a Cyclone from VDH, that covers all first stage components.
    Seller said it has new duckbill, and hoses.
    All I should need then is the body to can gasket (currently much debated up thread).... Everything else in the DAAM service "kit" would be obviated by the HPR and Cyclone?
    Thanks in advance
    James
     
  9. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    2,870
    1,022
    113
    You may need the high pressure (intermediate pressure) diaphragm and diaphragm washer.
     
  10. James79

    James79 Regular of the Pub

    # of Dives: 25 - 49
    Location: Lower Alabama
    261
    203
    43
    Are they the same as the Conshelf HP diaphragm? If so I have a small stock of them.
     

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