• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Tank valves needed

Discussion in 'Tanks, Valves and Bands' started by mac64, Nov 6, 2019.

  1. mac64

    mac64 Barracuda

    # of Dives: 5,000 - ∞
    Location: Ireland
    277
    92
    28
    hope someone can help with this, I'm looking to split an old 12ltr. steel twin set with the intention of side mounting them. I need to buy valves but can't find any measurements on the old valves. The only numbers that are stamped on are 0022. The measurements I've taken from the neck where they tread into the tank are 1 1/32 inch (26.2mm) and 14TPI. My reason for going side mount is there to heavy on land or I'm to old, IMG_1150.JPG
     
  2. James79

    James79 Regular of the Pub

    # of Dives: 25 - 49
    Location: Lower Alabama
    251
    184
    43
  3. mac64

    mac64 Barracuda

    # of Dives: 5,000 - ∞
    Location: Ireland
    277
    92
    28
  4. James79

    James79 Regular of the Pub

    # of Dives: 25 - 49
    Location: Lower Alabama
    251
    184
    43
    No worries... Only other thing I just thought of, I've heard some of Europe uses a metric thread that is very similar, but I don't know enough about those to conclusively tell yours isn't metric.
     
    mac64 and michael-fisch like this.
  5. michael-fisch

    michael-fisch Manta Ray

    # of Dives: 2,500 - 4,999
    Location: Germany
    674
    403
    63
    European cylindirical Tank threads are M25 x 2.

    Michael
     
    James79 likes this.
  6. mac64

    mac64 Barracuda

    # of Dives: 5,000 - ∞
    Location: Ireland
    277
    92
    28
    Michael do you think I should scrape the paint of the neck of the cylinder to see if I can find some stamped measurements. Thanks
     
  7. W W Meixner

    W W Meixner Rebreather Pilot

    # of Dives: 500 - 999
    Location: Ontario Canada
    737
    507
    93
    Mac...

    Certainly looks like a standard 3/4-14...I'm sure your LDS has lots of standard scrap valves that you can test fit...

    Just don't force it...if it's standard 3/4-14...the valve will either thread right in or it won't...

    Cylinder stampings North America don't include thread size...what you can check for is a Certification stamp/number...for use in the US its DOT...for Canada it's TC...determine what your certification requirement is for Ireland...if it does not have it...you will not be able to fill the cylinders commercially...either way the cylinders will need to be re-hydro'd...and current annual visual inspection...

    A lot of ''old''...''vintage'' doubles set ups used re-purposed cylinders...medical/military...etc...so certification ID on the cylinders will be important...

    Your local re-hydro inspection operator will give you all the information you need...

    Good Luck...

    W.W...
     
  8. mac64

    mac64 Barracuda

    # of Dives: 5,000 - ∞
    Location: Ireland
    277
    92
    28
    Thank you for your reply, I’ll clean the neck of one of the tanks and see what markings I find. I’ll also check some scrap valve, great advice thanks.
     
  9. michael-fisch

    michael-fisch Manta Ray

    # of Dives: 2,500 - 4,999
    Location: Germany
    674
    403
    63

    Wouldn't bother.

    M25x2 has a max exterior dimension of 25mm. a US 3/4" valve will jam as you thread it into a M25 tank.

    The other way is more problematic:

    A M25 valve can be screwed into a 3/4 x 14 threaded tank, the fit is a bit sloppy (since M25 is just a bit smaller) and after the first few turns it'll become harder to finally thread the valve all the way in. (difference between 12.7 threads per inch on the metric valve and 14 threads per inch on the tank).
    If you are a fool don't despair, it is possible to screw a M25 valve into a 3/4 x 14 tank and the fitting will hold gas untill the valve shoots out as the tank pressure approaches 150Bar (2250 psi). When this happens (and it happens approximately twice a year in Europe), people are killed, maimed or severely injured and the room where the fill station WAS is usually pretty well destroyed.

    Michael
     
  10. mac64

    mac64 Barracuda

    # of Dives: 5,000 - ∞
    Location: Ireland
    277
    92
    28
    Thanks Michael, the valve that I need is bigger than 25mm (26.2 mm) I’ll try to pick up an old 3/4 14 and see how it fits, the valve I need is definitely 14 TPI
     

Share This Page