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In pursuit of understanding the center balance poppet.

Discussion in 'Regulators' started by lexvil, Aug 28, 2020.

  1. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    having joined the “D” club with the Scubapro D420 after years of ignoring the concept, since the tried and true in-line system balanced regs like the BA was always “good enough” and easy to service and adjust, the D just seemed weird, I had the D400 for years but never used it, finally traded off the excitement from some here over the “new” D made me look again and it’s didn’t start off well, all covered in the super long and still going D420 thread. Early adoption usually comes with problems and adjusting pains and the 420 was not only no exception but sort of a poster child for this yet with some tuning and a lot of experimental tweaking it has turned out to be a really amazing performer “in the water” and with the James79 adjuster allowing for in water adjusting the performance in great.

    Rob Singler has (@rsingler) dome some videos explaining the advantages of the D series regulators and the lower position of the diaphragm for ease and utter smoothness of breathing from these types of regulators.

    I wanted to get a better understanding oof this “system” so I figured to go to the beginning, the Scubapro A.I.R.1
    C38F13BC-856D-4DC0-81B6-7F935D43B19B.jpeg 4F4741F8-CAE8-4AFD-A49B-F12694A4D525.jpeg
    There is very little information on these the first SP of this type, the Pilot was a similar concept but with a completely different valve design (my understanding anyway) that was often converted the the AIR1 guts.
    8DEDF89F-762C-4847-945C-2BA2F52D8784.jpeg
    In the water the AIR1 is simply amazing, all you need to do to breath is start thinking about it, no effort, no cracking etc. you just breath! Diaphragm placement can’t be the only reason although that along with the short path of air travel have or get most of the credit, I did look at the orifice of a “conventional” regulator, here is as best as I can measure the orifice opening of the center balance
    C2B025AD-6FBF-4254-8841-E7F4559BDFE5.jpeg
    And this is the “conventional” orifice (Zeagle in this case, will go check a SP one later) the surface area may be part of the delivery improvement (?)
    312C99A3-17E7-44C7-97A6-CF870B03190C.jpeg
    One of the more weird in the AIR1 (also the pilot I believe) was no exhaust valve! Other than this area of the main diaphragm (somewhere around 90° or less) the majority of the diaphragm is also the exhaust valve! (Weird concept)
    16213C87-28A9-4760-BF65-5F709672DBE9.jpeg
    The cover for this otherwise one piece case is also a guide/alignment for the main diaphragm to keep it from misbehaving during its dual use.
    7F3C4663-864C-40E8-BE4F-53DD15123D51.jpeg
    Adjusting lever height is easily done without removing the diaphragm clip, just pull it out of the way and adjust, this is a critical adjustment for the design, there is also a spring adjustment in the top cap for fine tuning.
    9D17DB3B-1904-4C78-B793-41D1A1CDAB5F.jpeg
    It turns out the G250 cover tool works perfectly for these.
    F2A5D67D-9BE0-4A1D-8615-5EB38DCAB3A1.jpeg
    I’m not into vintage for vintage sake, this is about performance, this was as big a breakthrough as they said “back in the day” I now have 4 of these “antiques” and have them on pony bottles where the flatness fits the role perfectly.
    942B401E-5096-4E55-AF80-DBE4A0AF4477.jpeg
    The D420 follows the same concepts, I still don’t know why it’s dry performance is so poor compared to its ease of use in the water, they didn’t make major changes over the original design, mostly a small change the the valve body poppet centering. The old AIR1 uses the poppet from the D400 as a direct swap and the later ones that are rebuildable can keep a lot of those things going for some time yet. I like this design over the D300/350/400 because the lack of the big rubber exhaust port that makes up the majority of the case, when these fail there are no replacements so you have to scrap one to save one.
     
    jale, axxel57, Kupu and 3 others like this.
  2. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    One of them out for a pony ride, used for about 15 minutes of an 85 minute dive, flatness and great performance along with extreme ease in changing hose input side make these really nice for a pony reg.

    E03796C1-51CD-4B7C-8112-017A2A3F6C47.jpeg CB29977F-0FBB-4211-A530-164134FC7E27.jpeg
     
  3. EdTeach

    EdTeach Angel Fish

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    Yes, the Air 1 is an amazing regulator. I began using them in the early '90's when Scubapro was selling them at 1/2 price after the introduction of the D300. I prefer the Air 1's to the D Series regulators. Air 1's breathe easier on both inhalation and exhaust, in my opinion. I have many Air 1's and a number of D300's, 350's and 400's.

    The only better breathing regulator than the Air 1 that I have tried is the Pilot. It is nearly effortless on inhalation due to the pilot-assist design. Theoretically, the Air 1 should be a bit better on exhalation since it has the same diaphragm / exhaust valve design as the Pilot in a molded plastic body, which should afford smoother flow. I can't tell any difference in exhalation effort between the two and haven't made an objective measurement.

    How does the Air 1 stack up to the D420?
     
  4. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

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    Yeah, It was owning a Pilot (converted), a couple Ait1, and a couple D300/350/400 series that really didn't motivate me to get a 420...

    Parts availability for service became the only reason...
     
    lexvil likes this.
  5. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    I would rate the 420 as a worthy grand child to the AIR1, once tuned it will crack with no effort (my new one is very very close to the one with the James79 tuner, only the slightest difference that I can only tell by switching between them on a dive) and make sure you switch the mouthpiece, the factory one just didn’t feel right.

    Exhalation effort is not something I really ever notice all three center balance types are pretty effortless but the AIR1 is probably the leader unless you go head down in which case the A1 will breath wet, so long as you know that it’s not a big deal but the D’s were an overall improvement.
     
    axxel57 and rsingler like this.
  6. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    This is where the 420 leads but the good news is the seat and the poppet appear to be the same, the seat carrier is different but it looks like the poppet can be used to upgrade an older reg from the replaceable one piece unit to the 420 metal poppet and a D400 seat carrier, I have a few 420 kits and whenever I need to service one I will try the parts swap (or if SP offers the 420 poppet assembly separate from the kit) I have D400 poppets in two of my A1’s, two with red top poppets and two with the original style, the older type are still working but the seat won’t last forever.
     
    rhwestfall likes this.
  7. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

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    @lexvil - how are you addressing the switch on the front of the Air1? The square o-ring as well as the removal/replacement? I know you can switch in a round o-ring, but my experience has been that I think there is a leak if the label is missing...

    I was going to try to get someone to do a run of metallic "stickers" of a dimension to fit that switch, but got sidetracked on life.... not sure who I would go to now....

    been a couple years since I played with my Air1/D-Series regs.
     
  8. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    The 6 I have are all intact and I’m not going to mess with the so long as they are. SP from what I can dig up in the scant info available, didn’t recommend messing with them regularly and to replace the entire thing if removed, a bridge I haven’t come to yet but I have considered asking James79 what he thinks about it.
     
  9. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

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    Some of my early acquisitions had the o-ring dry rotted, and crumbling....
     
  10. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    You are ahead of me in finding a solution!
     
    rhwestfall likes this.

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