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1/2in NPS valve required for 72

Discussion in 'Vintage Equipment Diving' started by Zodiacdiverdave, Sep 4, 2010.

  1. ScubaBunga

    ScubaBunga Nassau Grouper

    # of Dives: 500 - 999
    Location: wright city, mo
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    is there a standard oring size for these 1/2” threads?
     
  2. abnfrog

    abnfrog Tech Instructor

    # of Dives: 2,500 - 4,999
    Location: great white north
    1,875
    1,501
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    half inch
     
  3. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    I wonder whether some of the threads in this old thread are actually M18.
     
  4. apenland01

    apenland01 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 25 - 49
    Location: Tucson AZ
    160
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    I just picked up a Norris 2250 72 with an original hydro of 1975. What valve is this going to have? I took it in for visual and hydro yesterday and need to put a DIN valve in it. The guy that I got the tank from gave me a DIN valve to replace the old yoke valve. Any idea where I can find definitive information on this tank?
     
  5. James79

    James79 Reinventor of Wheels ScubaBoard Supporter

    # of Dives: 50 - 99
    Location: Lower Alabama
    763
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    As far as I know, there were only 3 neck threads used on the old 72s... 1/2 NPT (taper thread, easily recognized by the exposed threads when installed), 1/2 NPS (uncommon; Sportsways, Healthways, and White Stag.... And only for a short time period. Recognizable by an unusually narrow neck.), and 3/4-14 (modern standard). With a 1975 born on date, I'd bet you a dollar it's 3/4-14. Incidentally, those designations are based on pipe inside diameters, so a 3/4-14 valve actually measures a little over 1 inch at the threads.
    Respectfully
    James
     
    captain, apenland01 and Luis H like this.
  6. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    I have never seen a 1/2 NPSM thread on a cylinder and am skeptical that this thread form was actually used. M18x1.5 threads were used on some earlier (1960s) scuba cylinders including some I have had in my possession; I confirmed the thread size by using an M18x1.5 tap as a thread gauge.

    M18 threads are also used on SCBA cylinders. They are slightly smaller than 7/8" UNF.
     
  7. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
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    Below are pages from the 1961, 1962 and 1963 Sportways catalogs. They all refer to 1/2" Standard Pipe Thread and 3/4" straight thread.

    In 1961 it is fairly safe to assume that we did not use any metric threads in the US.

    An interesting thing that is not normally known is that even the DIN connection that has been very popular in Europe (and recently made it to the US) also predates the use of metric threads. The DIN fitting uses Imperial threads. When I started using the DIN fitting in the 70's it was not even called DIN at the time.



    Pages from Sportsways 1961.jpg


    Pages from Sportsways 1962_Page_1.jpg


    Pages from Sportsways 1962_Page_2.jpg


    Pages from Sportsways 1963.jpg
     
    rjack321 likes this.
  8. apenland01

    apenland01 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 25 - 49
    Location: Tucson AZ
    160
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    Thank you! The valve on it was a yoke valve that looked pretty standard and there were no exposed threads. The DIN valve I took to the shop for them to replace was a straight valve that measured just over an inch wide at the threads. It had an O-ring at the top of the threads. It sounds like it should work just fine. Thanks!
     
    James79 likes this.

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