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solution for D-series poppet seat DIY?

Discussion in 'Repairing your own Gear' started by Kupu, Sep 17, 2020.

  1. happy-diver

    happy-diver Skindiver Just feelin it

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    Magnificent!
     
  2. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    It works great!
    20201024_134840.jpg
    I've posted some comments here:
    D420! How about that?
     
    lexvil, couv and Kupu like this.
  3. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    Update on the @Kupu poppet:
    After sitting for three weeks on a restored orifice (not knife sharp like the original, but polished as smooth and tight a radius as I could get) tuned for 0.55", the tune held, but the seal did not. :banghead:
    Intermittently, the poppet would freeflow every so slightly, and all the purging and sharp exhaling I could do didn't stop it. However, if I turned off IP and depressurized the reg, it would seal right up again. And then, after a few very light breaths and a couple of sharp inhales, it would unpredictably hiss again. Grrr!
    IMG_20201106_141203.jpg
    I've raised the tune to 0.65" and it seems to have fixed the issue. So maybe 0.65" with this knife edge is the best I can do. We'll see...
     
    axxel57, couv, Kupu and 1 other person like this.
  4. Kupu

    Kupu Polliwog ScubaBoard Supporter

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    Thanks for the update, it has been a few weeks since I looked at my AIR1s with oring seats.
    One had seatsaver key installed and is still good, another sitting without the key installed now has a steady freeflow.
     
  5. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    Follow up on the 420
    Last week while nearing the end of my second dive I felt that there was a change in breathing and at the end of the dive I couldn’t fully purge the remaining air while breaking things down. I have 12 to 15 hours on the o ring seat, decided to see if the o ring had been cut or damaged so I took the reg apart, the o ring looked fine, no cut or any other sign of damage. I switched the oring seat for another and it blew out, switched again and the tightness of the locknut is truly critical and it tuned up nicely but a full purge wasn’t happening.

    Now setting back up with the original seat as this experience is thought over. The softness which allowed such a nice tune and the rounded shape is likely what caused the purge issue and the blow out if the nut is to tight or loose. I’m wondering why the dry, in shop breathing was so much smoother with the 104 and diving performance was noticeably better but only slightly. I am assuming that the softness and rounded shape are not only responsible for the great breathing but also the lack of full purge.
     
    Kupu and couv like this.
  6. Kupu

    Kupu Polliwog ScubaBoard Supporter

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    Too bad this has not turned out to be a home run. Not sure when I will have time to play with this again, but curious how orings of other materials and hardness will perform.

    If all else fails, I think this could still work quite well as hobby solution with my AIR1s and converted pilot. It seems likely the tune will hold long term with use of seat saver keys. One point for those regulators compared to the older D's is how easy it is to access the set screw for adjusting, installing new seat and tuning takes under 5 mins.

    Thanks to lexvil for additional comments on how the oring is working in the D420.
     
    lexvil likes this.
  7. GJC

    GJC Solo Diver

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    I
    I wonder if the stacked o rings are settling in/partially extruding themselves under pressure as they cycle with breaths. Relieving the IP pressure would allow them to go back into position to seal up again.

    I also wonder if the seal to the poppet shaft is the leak rather than the seat to orifice.

    Maybe some very involved testing coming up with a variety of slightly different size and duro o rings?
     
    Kupu likes this.
  8. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    Correct on both counts.
     
  9. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

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    I'm going to try a wisp of silicone RTV sealant in between the orings, before I screw on the nut. I'm determined to make @Kupu's solution work!

    @GJC, good thought about varying o-ring hardness! While the original patented seat was Duro 55 (so @Kupu's choice was near-perfect), I'm wondering if a softer 1x3mm supporting the -104 at the poppet stem shelf might conform better to the -104 during cycling. That and the "glue" in lieu of that bonded metal disc that Scubapro manufactured.

    Stand by...
     
    lexvil and Kupu like this.
  10. Kupu

    Kupu Polliwog ScubaBoard Supporter

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    The idea of trying different materials and oring combinations etc is good.

    I believe my freeflow resulted from a slight groove in the oring seat plus very light tuning of .3" rather than leak around the poppet stem. With that in mind, I have repeated the experiment with three AIR1s, all tuned to .3" and then installing seat saver. They are stashed away unused, too be checked every month or two until next summer when my dive season resumes. If they hold up over time or not, that should give some data to work with.

    Regarding the 1X3mm oring, I wonder if my approach of using the original 1x2.5mm oring vs a 1x3mm might have the benefit of creating a more durable seal around the poppet stem. Forcing the 1x2.5mm onto the wider section of the stem under the -104 seat could create a tighter seal around the stem at the same time it seals against the -104. Just a thought, based on what seems to be working for me so far.

    Happy for the continued ideas and feedback!
     
    axxel57, couv and lexvil like this.

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