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ATX DS4 first stage blow out!

Discussion in 'Apeks' started by partha, Mar 3, 2020.

  1. O-ring

    O-ring Beyond the Pale ScubaBoard Supporter

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    Yeah, I would expect it to make a heck of a hissing sound like a yoke valve o-ring does when someone doesn't screw the first stage on all the way before turning on the tank. Maybe because it is captured down in the body of the first stage the gas couldn't get out fast enough (like it does on all sides of a yoke) so it blew off? We'll never know for sure unless Tursiops tests it. :p

    Tursiops - if it hisses then redo the test, but make sure you open the valve real fast.
     
  2. jgttrey

    jgttrey ScubaBoard Supporter ScubaBoard Supporter

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    Assuming threads are intact, the only way it could have blown off (by definition) is if it was almost entirely unscrewed. Otherwise, the threads would be trashed.

    Having a leak in that spot is not uncommon on any DIN reg. If an inexperienced diver attempts to loosen the first stage from the tank by turning the body of the first stage rather than the handwheel, then it is easy to unscrew the first stage body from the DIN connector rather than unscrewing the whole assembly from the cylinder valve. This often happens when the system is still partially pressurized because somebody didn't do a good purge.

    If it does happen, and you hear the pop/hiss of air (or when you hook it up next time and get a leak in that spot), be aware that simply retightening is not good practice. It is likely that the oring extruded and needs to be replaced. As I said, the o-ring is just the standard size of an LP port. You need to unscrew the entire assembly, replace the oring and torque down. It really couldn't be easier, provideed you a way to hold the first stage body while you torque.

    To be honest, I wouldn't get balled up about exactly how many foot pounds or newton meters. Past the first bit, it doesn't have anything to do with the quality of the seal, only how resistant it will be to user error of the type that must have occurred here.
     
  3. Zef

    Zef Divemaster

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    The way these things often unscrew is that folks without experience with DIN regulators will attach the regulator and tighten down the DIN handwheel. Then they find that the hoses are not aligned the way they want and instead of loosening the handwheel they turn the 1st stage body....if they continue to muck around with this repeating the process, they can windup unscrewing the DIN connector from the 1st stage enough that it can blow off as it did. Usually this doesn't happen because the the hoses get aligned, the valve is opened and leaks and the valve is then shut and troubleshooting occurs, but since this is a student, then perhaps they didn't open the valve right away and continue to mess with it causing it to unthread enough to blow off. The typical result is a leak, but when dealing with folks that have little hands on experience with equipment typical is what one hopes for but does not always get.

    -Z
     
  4. divad

    divad Solo Diver

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    Guilty....a long time ago. The worst I got was a tiny bubble before I figured it out. Nothing looked "off" until I checked it with a hex key, which is why I just always check them (doubles) before attaching 1st stages.
     
  5. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    I hope you are still waiting....real soon now.
     
    O-ring likes this.
  6. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    I think not. It should be duro 90 for tank pressure and a face seal.

    EDIT: I take it back. You're right!
    Will have to go take a feel of AP1409P and see if it feels like duro 70 or 90. It IS the same as the LP Port oring. My apologies.
     
  7. JackD342

    JackD342 Dive Shop

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    I can't speak to the duro, but Apeks and Aqualung kits both use the same O-rings for the filter retention as for the LP hose/port connections. Both DIN and yoke.
     
  8. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    I believe duro 90 is the default for all high pressure seals.
     
  9. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    Really? I'll have to go look at the schematic. Is that o-ring adjacent to the filter the oring that seals the DIN connector to the body? If so, I'd think that a duro 70 LP port o-ring would be prone to extrusion in the DIN connector.
    Time to get the schematics out...
     
  10. JackD342

    JackD342 Dive Shop

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    Yep, the o-ring is captured at the seal. But remember you actually have a metal to metal connection rather than a significant compression of the o-ring to form the seal. The o-ring is recessed into the connector (or body for some yoke versions) and does not really have a space to extrude. Of course, they might also just be using a higher than necessary duro o-ring for the LP ports. Also the same o-ring on the removable HP crown for Apeks. Different o-ring for the crown with Aqualung.
     
    rsingler likes this.

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