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Scubapro G250 can't be serviced??

Discussion in 'Regulators' started by SlyStrat, Apr 2, 2021.

  1. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    5,644
    7,199
    So, I switched balance chambers to see what the difference in minimum cracking effort was (knob fully out position). The difference in base height as measured by @Open Ocean Diver was 0.024"/0.6mm. That's less than a half turn on the knob. I started with the old style, shorter base chamber and a cracking effort of 1.05". Sure enough, when I put the taller base balance chamber in my G250, the min cracking effort went from 1.05" to 1.12" measured with the precision cracking effort pump. It all makes sense, if not really significant. On the other hand, I'd rather be able to get 1" min on my G250 than 1.1", so there's that.

    As for which balance chamber clears the wiper o-ring, here's a picture:
    20210405_095703.jpg
    As you can see, in my reg, there's 79.5mm clearance from the knife edge of the orifice to the locking pin hole in the barrel.
    When the pieces are set out at that distance with the old balance chamber, the wiper o-ring is just inside the crown, and thus performing its function. More surprising is the amount of compression on that poppet spring. It's fully 1/3 compressed in its least compressed position.

    My conclusion? For the G250 at least, it doesn't matter which balance chamber you use, unless you want below spec cracking effort (which I do :D).
    One of these days I'll take a look at the G260...
     
  2. couv

    couv Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: 13th floor of the Ivory Tower
    6,019
    3,871
    Was the lower cracking effort achieved with the newer/longer balanced chamber or with the older/shorter balance chamber?
     
  3. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    5,644
    7,199
    Lower cracking effort with the old (shorter) balance chamber. Poppet spring less compressed. I edited my post for clarity.
     
    Pressurehead and couv like this.
  4. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    16,841
    20,244
    but if the base height dimension is the same, it makes no difference....

    upload_2021-4-5_13-56-13.png

    The "stem" length is irrelevant....

    right?

    Were your bases different heights?
     
  5. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    16,841
    20,244
    okay, there may be a difference...

     
  6. couv

    couv Instructor, Scuba

    # of Dives: 1,000 - 2,499
    Location: 13th floor of the Ivory Tower
    6,019
    3,871
    That's the way I see it. Shorter base = less spring compression.
     
  7. rhwestfall

    rhwestfall Woof! ScubaBoard Sponsor

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    16,841
    20,244
    Yes, that is true.

    That picture gave me pause there was a difference...
     
  8. Open Ocean Diver

    Open Ocean Diver ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Toronto, Lauderdale-by-the-Sea
    1,254
    823
    Even with the longer BC with IP135 both my G250V crack at .7, .8” can’t tune them to 1” without a spring shim. :banghead:
     
  9. buddhasummer

    buddhasummer Bat sh.t crazy

    # of Dives: 1,000 - 2,499
    Location: Nanny State
    12,101
    4,620
    Presumably you've tried various .216 and .218 springs?
     
  10. Open Ocean Diver

    Open Ocean Diver ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Toronto, Lauderdale-by-the-Sea
    1,254
    823
    Yes I have, maybe I just need to find that magical spring. I disorder checked calibration on my mag.
     

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